Check prime numbers instantly
Determine if any integer is prime and find its complete list of prime factors.
About This Tool
Prime Number Checker is useful for math students, competitive programmers, and developers working with cryptography or hashing algorithms that rely on prime numbers.
Key Features
Instant prime or composite result
Prime factorization display
List all factors
Handles large numbers efficiently
100% client-side
How to Use This Tool
- Enter any positive integer.
- The tool instantly tells you if it is prime.
- View the full prime factorization for composite numbers.
Why Use This Tool
- Instant primality test without manual trial division.
- Full prime factorization shown for composite numbers.
- Helpful for math coursework and algorithm problems.
Pro Tips
- Use for competitive programming problems involving primes
- Check if RSA key components are prime
- Factor numbers to find GCD manually
Frequently Asked Questions
Is 1 a prime number?
No. By mathematical definition, prime numbers must have exactly two distinct divisors: 1 and themselves. 1 has only one divisor.
What is prime factorization?
Prime factorization breaks a number into a product of prime numbers, e.g. 12 = 2 × 2 × 3.
What is the largest number I can check?
The tool works well up to numbers in the billions range directly in the browser.