Education
Prime Number Checker
Tells you if any number is prime, lists its factors, and shows the nearest prime numbers above and below.
Prime?
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- Factors
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- Next prime up
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- Next prime down
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FAQ
Why is 1 not prime? +
A prime has exactly two distinct positive divisors: 1 and itself. 1 only has one divisor, so it does not qualify.
Largest prime? +
There are infinitely many primes — Euclid proved it. The largest known prime as of 2026 has over 41 million digits.