Six hundred forty five
645 is an odd number.
645 is a Harshad number, which means it is divisible by the sum of its digits (6 + 4 + 5 = 15, and 645 is divisible by 15).
In binary, 645 is represented as 1010000101.
In hex, 645 is represented as 285.
Prime factorization of 645: 3 * 5 * 43.