Q: Is 21 a Prime Number?

 A: No, 21 is not a prime number.

Why is 21 not a prime number?

A prime number is a natural number, greater than one, that can only be divided by 1 and itself.

The number 21 can be evenly divided by 1 3 7 and 21, with no remainder.

Since 21 cannot be divided by just 1 and 21, it is not a prime number.


More Examples

Number 19202223
Prime? yesnonoyes
  • All positive natural numbers are either a prime number or a composite number (except the number 1, which is neither).

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