Is 441 a prime or composite number?

Any number whose digits add up to 9 or a multiple of 9 is divisible by 9. Since the numbers' digits also add up to a multiple of 3, 441 is also divisible by 3.

A complete list of all of the positive integer factors of the number is:

1, 3, 7, 9, 21, 49, 63, 147, 441
441 is a composite number. A Prime number has only 2 factors which are 1 and itself. Composite numbers are everything else except 1 and 0. 1 and 0 are neither prime, nor composite.