Eighteen

18 is an even number.

18 is a Harshad number, which means it is divisible by the sum of its digits (1 + 8 = 9, and 18 is divisible by 9).

In binary, 18 is represented as 10010.

In hex, 18 is represented as 12.

Prime factorization of 18: 2 * 3^{2}.