Which is prime 15,89,39,9

15 can be divided by 5

39 can be divided by 3

9 can be divided by 3

89 can only be decided by itself and 1 which means that it is prime

First, you must know the definition of a prime number. A prime number is a number whose factors is 1 and itself. The prime number in the list is 89 because the only factors is 1 and itself (1*89).

The prime number is 89.