Home » Aptitude » Numbers

Which of the following is not a prime number?

Correct Answer: 21

Explanation:

A prime number is a whole number greater than 1 whose only factors are 1 and itself.


 


Factors of 5 are 1, 5


Factors of 11 are 1, 11


Factors of 21 are 1, 3, 7, 21


Factors of 37 are 1, 37.


 


Hence, according to the definition of a prime number, 21 is not a prime number as it has more than two factors.


← Previous Question Next Question→

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion