27
27
27 and 31 are prime.
17, 23 and 31 are prime. 39 is not.
17, 23 and 31 are prime. 39 is not.
17, 19, 23, 29 and 31 are prime. 15, 21, 25 and 27 are composite..
29
29
51 is not a prime number: 3x17=51
39
41
Composite. Its prime factors are 23 and 31.
51 is composite number