Prime Number Checker
Enter a number to determine whether it is prime. Also displays the nearest prime numbers above and below your input for quick reference.
Result
Enter values to calculate
How to Use the Prime Number Checker
1
Enter any integer greater than 1.
2
Click Check.
3
See whether the number is prime and view nearby primes.
Frequently Asked Questions
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.
Is 1 a prime number?
No — by definition, prime numbers must be greater than 1. The smallest prime is 2.
How does the checker work?
It tests divisibility by all integers up to the square root of the number, which is sufficient to determine primality.