The product of three primes, 290 is a
sphenic number, and the sum of four consecutive primes (67 + 71 + 73 + 79). The sum of the squares of the divisors of 17 is 290. Not only is it a
nontotient and a
noncototient, it is also an
untouchable number. 290 is the 16th member of the
Mian–Chowla sequence; it can not be obtained as the sum of any two previous terms in the sequence. See also the Bhargava–Hanke
290 theorem. == References ==