Prime Number Checker

Is it prime? Plus the full prime factorization of any whole number.

Frequently asked questions

How do I check if a number is prime?

Type the number. It is prime if it is greater than 1 and has no divisors other than 1 and itself. The tool tests divisibility up to the square root, which is fast even for large numbers.

What is prime factorization?

Every whole number above 1 can be written as a product of primes (for example 360 = 2 cubed times 3 squared times 5). The tool shows that breakdown.

Does it run in my browser?

Yes, instantly and client-side.