252

252 = 2 x 2 x 3 x 3 x 7.

252 is the smallest number that is the product of two distinct numbers that are reverse of each other: 252 = 12 x 21.

252 = 2⁸ - 4.

252 is the third value of Ramanujan's tau function (A000594).

252 is a hexagonal pyramidal number.

If you flip a coin 10 times in a row, there are exactly 252 ways in which it can turn out that you get exactly five heads and five tails.

Source: Number Gossip