Question

Of the following mumbers,which one is prime 14,13,21,33

Answer 1

The prime number is 13

Answer 2

This is easy. 

The answer is: 13. 

Explanation:

A prime number is a number that is only divisible by one and itself. 
Let's list their divisors. 

14: 1,2,7,14
13:1,13
21: 1,3,7,21
33: 1, 3, 11, 33

We can see that 13 is the only one that is divisible by 1 and itself.