Numbers are identified as either prime or composite numbers, with the exception of one. To be classified as a prime number, a number must be greater than one and only divisible by one and itself.
Sixty-three, however, is not a prime number. It is divisible by the following multiple numbers: 1, 3, 9, 7 and 21.
All composite numbers, like 63, have prime divisors. The prime divisors of 63 are 3 and 7.Learn more about Numbers