21, no.
89, yes.
21 + 42 + 52 + 58 + 72 + 75 + 89 = 409
It can be. 21 is relatively prime with 32.
The prime factorization for 21 is 3x7.
Do you mean, "What is the prime factorization of 21?"
21 is not prime.
number 21 is prime
The prime factorization for 21 is: 3x73 x 7 = 21
3 * 7 = 21 21 is not prime
21 is a composite number, not a prime, having prime factors 3x7.
11 is a prime number but 21 is not a prime number as it is divisible by 3.
21 = 3x7, and so is not prime, as it can be expressed as the product of multiple prime numbers
3 x 7 = 21, since both factors are prime, that is the prime factorization of 21.