Take the help of our Prime Number Calculator and determine whether the given 21 number is prime or composite number. Within a fraction of seconds, our free online tool gives you an output as 21 is a Composite Number as it has 1, 3, 7, 21 factors.
Ex: 52 or 96 or 47
21 is a Composite Number and can be factored by any of the following numbers.
Factors of 21 are 1, 3, 7, 21
1. How to find 21 is prime or composite?
First, find the factor that is divisible by 2 and if you find factor 1 and itself then it is a prime or else composite number.
2. What are the factors for 21?
The factors of 21 are 1, 3, 7, 21.
2. Is 21 Prime or Composite?
21 is a Composite Number as it has 1, 3, 7, 21 factors then 21 is a Composite Number.