Prime Number Checker

What is a Prime Number?

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. The first few primes are 2, 3, 5, 7, 11, 13, 17, 19...

How to Use This Tool

Enter any positive integer and click "Check". The tool instantly determines if the number is prime and shows its factors if it's composite.

Prime Number Properties

• 2 is the only even prime number
• Every prime > 3 can be expressed as 6n ± 1
• There are infinitely many primes
• Primes become less common as numbers increase

Why Primes Matter

Prime numbers are fundamental to cryptography, especially RSA encryption used in secure communications. They also appear in number theory, puzzles, and mathematical research.

How to Check for Primes

To check if n is prime, test divisibility by all primes up to √n. If none divide evenly, n is prime.

FAQ

What is the largest known prime?
As of 2024, the largest known prime has over 41 million digits and was discovered using distributed computing.