17, 23 and 31 are prime. 39 is not.
17, 23 and 31 are prime. 39 is not.
29
29
39
27
51 is not a prime number: 3x17=51
27
Composite. Its prime factors are 23 and 31.
51 is composite number
23 29 31 and 37.
No. 31 is a prime number, and 72 is not a multiple of 31.