math
Prime Number Checker
Check whether a whole number is prime, and see its smallest factor if it is not.
Result
Prime
97 has no divisors other than 1 and itself.
How it works
- 1Enter a whole number.
- 2The checker tests divisibility up to the square root of the number.
- 3See whether it is prime, or the smallest factor if it is composite.
Use cases
- Check whether a number is prime for math homework.
- Verify a prime before using it in cryptography practice.
- Find the smallest factor of a composite number.
Frequently asked questions
What is a prime number?
A whole number greater than 1 whose only divisors are 1 and itself. 2, 3, 5, 7, and 11 are the first primes.
Is 1 prime?
No. By definition a prime must be greater than 1, so 1 is neither prime nor composite.
How is primality tested?
By trial division: if no number up to the square root divides it evenly, the number is prime.
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