103 is a prime number, and the largest prime factor of 6!+1=721=7\cdot 103. The previous prime is
101. This makes 103 a
twin prime. It is the fifth
irregular prime, because it divides the numerator of the
Bernoulli number B_{24}=-\frac{236364091}{2730}=-\frac{103\cdot 2294797}{2730}. The equation 64^3+94^3=103^3+1 makes 103 part of a "Fermat near miss". There are 103 different connected
series-parallel partial orders on exactly six unlabeled elements. 103 is conjectured to be the smallest number for which repeatedly reversing the digits of its
ternary representation, and adding the number to its reversal, does not eventually reach a ternary
palindrome. ==References==