Prime Number Checker
Test primality and find the neighboring primes of any number.
97 is
Prime
Next prime
101
Previous prime
89
Checking primality
A number is prime when nothing but 1 and itself divides it. Trial division only needs to test up to the square root — any factor above it pairs with one below. 97 survives tests by 2, 3, 5, and 7, and √97 < 10, so it's prime.
Primes without end
Euclid proved primes never run out, yet they thin gradually (about 1 in ln n near n). Their unpredictable spacing is unsolved mathematics — and their multiplication-easy, factoring-hard asymmetry secures modern encryption.
Frequently asked questions
- How does the Prime Number Checker work?
- Test primality and find the neighboring primes of any number.
- Is the Prime Number Checker free to use?
- Yes. The Prime Number Checker is completely free, runs entirely in your browser, and requires no account or sign-up. Your inputs never leave your device.
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