399

399 = 3 x 7 x 19.

399 is 333 in base 11.

399 is the total number of parts in all partitions of 12.

399 is the smallest Lucas-Carmichael number.

399 = 7¹ + 7² + 7³.

399 is the smallest number, all of whose prime factors are of the form 4n + 3, whose sum of distinct prime factors is prime (3 + 7 + 19 = 29).

399 is the sum of 11 consecutive primes: 399 = 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47 + 53 + 59.

Source: Number Gossip