Prime Number Calculator

Check whether a whole number is prime or composite with our free Prime Number Calculator.

Enter a number to see whether it is prime, along with its factors and a simple explanation of the result.

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Enter a whole number to determine whether it is prime or composite.

Number Enter a whole number greater than 1.

A prime number is a whole number greater than 1 that has exactly two positive factors: 1 and the number itself.

For example, 7 is prime because its only positive factors are 1 and 7.

In contrast, 12 is not prime because it can be divided evenly by 1, 2, 3, 4, 6, and 12.

Example 1: 13 is prime because its only positive factors are 1 and 13.

Example 2: 29 is prime because it cannot be evenly divided by any whole number other than 1 and 29.

Example 3: 36 is composite because it has several factors, including 2, 3, 4, 6, 9, and 12.

1 is not a prime number. It has only one positive factor, while a prime number must have exactly two.

2 is the only even prime number. Every other even number greater than 2 is divisible by 2 and therefore is composite.

Negative numbers and non-whole numbers are outside the scope of this prime-number calculator.

The smallest prime number is 2.

No. The number 1 has only one positive factor, so it is not considered prime.

Yes. 2 has exactly two positive factors: 1 and 2.

No. Some odd numbers are composite. For example, 9, 15, and 21 are odd but are not prime.

A composite number is a whole number greater than 1 that has more than two positive factors.