728

728 = 2 x 2 x 2 x 7 x 13. It is the smallest number n where n and n + 1 are both products of five or more primes.

728 is 222222 in base 3 and 888 in base 9.

Consecutive Smith numbers are called Smith brothers: 728 is the smaller brother of the smallest pair (728 and 729) of Smith brothers. The sum of its digits is equal to the sum of the digits of its prime factors: 7 + 2 + 8 = 2 + 2 + 2 + 7 + 1 + 3 = 17.

728 is the sum of two distinct positive cubes: 728 = 8³ + 6³.

728 is the number of nodes in a regular 13-gon with all diagonals drawn.

Source: Number Gossip