Prime numbers and factorization
Find out if a number is prime, factor it into primes, see all its divisors and list the primes up to any limit.
How to useIs it prime? Prime factorization
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Prime numbers and factorization: what it is for
Type a number to find out if it's prime. If it isn't, the tool shows the prime factorization (like 360 = 2³ × 3² × 5), the number and list of divisors and the nearest primes.
It also lists every prime number up to the limit you choose, using the sieve of Eratosthenes.
How to use
- Type the number.
- See whether it's prime, its factorization and divisors.
- Adjust the limit to list primes.
When to use it
- Math homework.
- Finding the LCM and GCD by factorization.
- Studying number theory.
Frequently asked questions
What is a prime number?
A natural number greater than 1 that's only divisible by 1 and itself, like 2, 3, 5, 7 and 11. 1 isn't prime, and 2 is the only even prime.
How do I factor a number?
Divide by the smallest possible prime and repeat with the result until you reach 1. The primes you used are the factorization: 360 = 2³ × 3² × 5.
Is it really free?
Yes, 100% free. No sign-up, no subscription and no usage limits. All Tools123 tools are free and run right in your browser.