Prime Number Checker
Check if a number is prime and find prime factors
A prime number is a whole number greater than 1 that only divides evenly by 1 and itself. Enter a number to check whether it's prime and see its prime factors if it isn't.
97 is
Prime ✓
Next 5 Primes after 97
101, 103, 107, 109, 113
How to Use This Calculator
- Enter a whole number greater than 1.
- Read whether it's prime.
- If it isn't prime, review its prime factors.
Why Use This Calculator?
- Satisfying curiosity about whether a number is prime.
- Breaking a number into prime factors for simplifying fractions or number theory work.
- Checking a factor from a math problem.
Real-World Examples
Is 97 prime?
97 is prime: no whole number between 2 and its square root divides it evenly.
Factors of 12
12 = 2 × 2 × 3, so it's not prime, and those are its prime factors.
How the check works
To test a number, you only need to try dividing by primes up to its square root. If none divide evenly, the number is prime.
Frequently Asked Questions
Is 1 prime?
No. By definition, primes are greater than 1, and 1 is treated as its own special case.
What are prime factors?
They're the prime numbers that multiply together to make your number — like 2 and 3 for 12.
How large a number can I check?
Reasonably large numbers work, but very large inputs may take a moment or be impractical in a browser.
Important Disclaimer
Checks whole numbers greater than 1. Results are exact.
Privacy
Your entry stays in your browser and isn't sent or stored.
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