Is 57 a prime or composite number?

composite

. 57 divided by 3 is 19. (Any number in which all the digits add up to equal a number divisible by 3 is divisible by 3. 5+7=12 which is divisible by 3.) And since 57 is divisible by more numbers than just 1 and itself it is a composite number.
57 is a composite number since it can be divided by 3.

57/3 = 19
Composite.