800s • 801 = 32 × 89, Harshad number, number of clubs patterns appearing in 50 × 50 coins • 802 = 2 × 401, sum of eight consecutive primes (83 + 89 + 97 + 101 + 103 + 107 + 109 + 113),
nontotient,
happy number, sum of 4 consecutive triangular numbers (171 + 190 + 210 + 231) • 803 = 11 × 73, sum of three consecutive primes (263 + 269 + 271), sum of nine consecutive primes (71 + 73 + 79 + 83 + 89 + 97 + 101 + 103 + 107), Harshad number, number of partitions of 34 into Fibonacci parts • 804 = 22 × 3 × 67, nontotient, Harshad number,
refactorable number • "The 804" is a local nickname for the
Greater Richmond Region of the U.S. state of
Virginia, derived from
its telephone area code (although the area code covers a larger area). • 805 = 5 × 7 × 23,
sphenic number, number of partitions of 38 into nonprime parts • 806 = 2 × 13 × 31,
sphenic number, nontotient, totient sum for first 51 integers,
happy number, Phi(51) • 807 = 3 × 269, antisigma(42) • 808 = 23 × 101,
refactorable number,
strobogrammatic number • 809 = prime number,
Sophie Germain prime,
Chen prime,
Eisenstein prime with no imaginary part
810s • 810 = 2 × 34 × 5, Harshad number, number of distinct reduced words of length 5 in the Coxeter group of "Apollonian reflections" in three dimensions, number of non-equivalent ways of expressing 100,000 as the sum of two prime numbers • 811 = prime number, twin prime, sum of five consecutive primes (151 + 157 + 163 + 167 + 173), Chen prime,
happy number, largest
minimal prime in base 9, the
Mertens function of 811 returns 0 • 812 = 22 × 7 × 29,
admirable number,
pronic number, balanced number, the Mertens function of 812 returns 0 • 813 = 3 × 271,
Blum integer • 814 = 2 × 11 × 37, sphenic number, the Mertens function of 814 returns 0, nontotient, number of fixed
hexahexes. • 815 = 5 × 163, number of graphs with 8 vertices and a distinguished bipartite block • 816 = 24 × 3 × 17,
tetrahedral number,
Padovan number, Zuckerman number • 817 = 19 × 43, sum of three consecutive primes (269 + 271 + 277),
centered hexagonal number • 818 = 2 × 409, nontotient,
strobogrammatic number 820s • 820 = 22 × 5 × 41, 40th
triangular number, smallest triangular number that starts with the digit 8, Harshad number,
happy number, repdigit (1111) in base 9 • 821 = prime number,
twin prime, Chen prime, Eisenstein prime with no imaginary part, lazy caterer number ,
prime quadruplet with 823, 827, 829 • 822 = 2 × 3 × 137, sum of twelve consecutive primes (43 + 47 + 53 + 59 + 61 + 67 + 71 + 73 + 79 + 83 + 89 + 97), sphenic number, member of the
Mian–Chowla sequence • 823 = prime number,
twin prime,
lucky prime, the Mertens function of 823 returns 0, prime quadruplet with 821, 827, 829 • 824 = 23 × 103,
refactorable number, sum of ten consecutive primes (61 + 67 + 71 + 73 + 79 + 83 + 89 + 97 + 101 + 103), the Mertens function of 824 returns 0, nontotient • 825 = 3 × 52 × 11,
Smith number, the Mertens function of 825 returns 0, Harshad number • 826 = 2 × 7 × 59, sphenic number, number of partitions of 29 into parts each of which is used a different number of times • 827 = prime number,
twin prime, part of prime quadruplet with {821, 823, 829}, sum of seven consecutive primes (103 + 107 + 109 + 113 + 127 + 131 + 137), Chen prime, Eisenstein prime with no imaginary part, strictly non-palindromic number • 828 = 22 × 32 × 23, Harshad number, triangular matchstick number • 829 = prime number,
twin prime, part of prime quadruplet with {827, 823, 821}, sum of three consecutive primes (271 + 277 + 281), Chen prime,
centered triangular number 830s • 830 = 2 × 5 × 83, sphenic number, sum of four consecutive primes (197 + 199 + 211 + 223), nontotient, totient sum for first 52 integers • 831 = 3 × 277, number of partitions of 32 into at most 5 parts • 832 = 26 × 13, Harshad number, member of the sequence Horadam(0, 1, 4, 2) • 833 = 72 × 17,
octagonal number , a
centered octahedral number • 834 = 2 × 3 × 139,
cake number, sphenic number, sum of six consecutive primes (127 + 131 + 137 + 139 + 149 + 151), nontotient • 835 = 5 × 167,
Motzkin number • 836 = 22 × 11 × 19,
weird number • 837 = 33 × 31, the 36th generalized heptagonal number • 838 = 2 × 419, palindromic number, number of distinct products ijk with 1 3 × 3 × 5 × 7,
highly composite number, smallest number divisible by the numbers 1 to 8 (lowest common multiple of 1 to 8), sparsely totient number, Harshad number in base 2 through base 10,
idoneal number, balanced number, sum of a twin prime (419 + 421). With 32 distinct divisors, it is the number below
1000 with the largest amount of divisors. • 841 = 292 = 202 + 212, sum of three consecutive primes (277 + 281 + 283), sum of nine consecutive primes (73 + 79 + 83 + 89 + 97 + 101 + 103 + 107 + 109),
centered square number,
centered heptagonal number,
centered octagonal number • 842 = 2 × 421, nontotient, 842!! - 1 is prime, number of series-reduced trees with 18 nodes • 843 = 3 × 281,
Lucas number • 844 = 22 × 211, nontotient, smallest 5 consecutive integers which are not squarefree are: 844 = 22 × 211, 845 = 5 × 132, 846 = 2 × 32 × 47, 847 = 7 × 112 and 848 = 24 × 53 • 845 = 5 × 132, concentric pentagonal number, number of emergent parts in all partitions of 22 • 846 = 2 × 32 × 47, sum of eight consecutive primes (89 + 97 + 101 + 103 + 107 + 109 + 113 + 127), nontotient, Harshad number • 847 = 7 × 112,
happy number, number of partitions of 29 that do not contain 1 as a part • 848 = 24 × 53,
untouchable number • 849 = 3 × 283, the Mertens function of 849 returns 0,
Blum integer 850s • 850 = 2 × 52 × 17, the Mertens function of 850 returns 0, nontotient, the sum of the squares of the divisors of 26 is 850 . The maximum possible
Fair Isaac credit score, country calling code for North Korea • 851 = 23 × 37, number of compositions of 18 into distinct parts • 852 = 22 × 3 × 71,
pentagonal number, Smith number the
Mertens function of 853 returns 0, average of first 853 prime numbers is an integer , strictly non-palindromic number, number of connected graphs with 7 nodes • country calling code for Macau • 854 = 2 × 7 × 61,
sphenic number, nontotient, number of unlabeled planar trees with 11 nodes • 855 = 32 × 5 × 19,
decagonal number,
centered cube number • country calling code for Cambodia • 856 = 23 × 107,
nonagonal number,
centered pentagonal number,
refactorable number • country calling code for Laos • 857 = prime number, sum of three consecutive primes (281 + 283 + 293), Chen prime, Eisenstein prime with no imaginary part • 858 = 2 × 3 × 11 × 13,
Giuga number • 859 = prime number, number of planar partitions of 11,
prime index prime 860s • 860 = 22 × 5 × 43, sum of four consecutive primes (199 + 211 + 223 + 227), Hoax number • 861 = 3 × 7 × 41, sphenic number, 41st
triangular number, Smith number • 864 = 25 × 33,
Achilles number, sum of a twin prime (431 + 433), sum of six consecutive primes (131 + 137 + 139 + 149 + 151 + 157), Harshad number • 865 = 5 × 173 • 866 = 2 × 433, nontotient, number of one-sided
noniamonds,
number of cubes of edge length 1 required to make a hollow cube of edge length 13 • 867 = 3 × 172, number of 5-chromatic simple graphs on 8 nodes • 868 = 22 × 7 × 31 =
J3(10), nontotient • 869 = 11 × 79, the Mertens function of 869 returns 0
870s • 870 = 2 × 3 × 5 × 29, sum of ten consecutive primes (67 + 71 + 73 + 79 + 83 + 89 + 97 + 101 + 103 + 107), pronic number, 103 – 53 • 876 = 22 × 3 × 73, generalized pentagonal number • 877 = prime number,
Bell number, Chen prime, the Mertens function of 877 returns 0, strictly non-palindromic number, • 879 = 3 × 293, number of
regular hypergraphs spanning 4 vertices, candidate
Lychrel seed number
880s • 880 = 24 × 5 × 11 = 11!!!, Harshad number; 148-
gonal number; the number of
n×
n magic squares for n = 4. • country calling code for Bangladesh •
881 = prime number,
twin prime, sum of nine consecutive primes (79 + 83 + 89 + 97 + 101 + 103 + 107 + 109 + 113), Chen prime, Eisenstein prime with no imaginary part,
happy number • 882 = 2 × 32 × 72 = \binom{9}{5}_2 a
trinomial coefficient, Harshad number, totient sum for first 53 integers, area of a square with diagonal 42 • 885 = 3 × 5 × 59,
sphenic number, number of series-reduced rooted trees whose leaves are integer partitions whose multiset union is an integer partition of 7. • 886 = 2 × 443, the Mertens function of 886 returns 0 • country calling code for Taiwan • 887 = prime number followed by primal
gap of 20, safe prime, • 889 = 7 × 127, the Mertens function of 889 returns 0
890s • 890 = 2 × 5 × 89 = 192 + 232 (sum of squares of two successive primes), sphenic number, sum of four consecutive primes (211 + 223 + 227 + 229), nontotient • 891 = 34 × 11, sum of five consecutive primes (167 + 173 + 179 + 181 + 191),
octahedral number • 892 = 22 × 223, nontotient, number of regions formed by drawing the line segments connecting any two perimeter points of a 6 times 2 grid of squares like this . • 893 = 19 × 47, the Mertens function of 893 returns 0 • Considered an unlucky number in
Japan, because its digits read sequentially are the literal translation of
yakuza. • 894 = 2 × 3 × 149, sphenic number, nontotient • 895 = 5 × 179, Smith number, the Mertens function of 895 returns 0 • 896 = 27 × 7,
refactorable number, sum of six consecutive primes (137 + 139 + 149 + 151 + 157 + 163), the Mertens function of 896 returns 0 • 897 = 3 × 13 × 23, sphenic number, Cullen number • 898 = 2 × 449, the Mertens function of 898 returns 0, nontotient • 899 = 29 × 31 (a
twin prime product),
happy number, smallest number with digit sum 26,
number of partitions of 51 into prime parts == References ==