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Math Calculators

Prime Number Checker

Test whether a whole number is prime. If it is not, you get its prime factorisation, how many divisors it has, and the nearest primes on either side.

9,973PrimeOnly divisible by 1 and itself
Prime factorisation
9973
Number of divisors
2
Previous prime
9,967
Next prime
10,007
Step-by-step working
  1. Tested divisors up to √9,973 ≈ 99.
  2. None divide evenly, so 9,973 is prime.

How to use the Prime Number Checker

  1. Enter a whole number from 0 to 1,000,000,000,000,000.
  2. Press Calculate.

Formula

A prime is a whole number greater than 1 whose only divisors are 1 and itself. It is enough to test divisors up to √n, because any larger factor would pair with a smaller one already tested.

Examples

  • 97 is prime: no number from 2 to 9 divides it.
  • 360 = 2³ × 3² × 5, with (3+1)(2+1)(1+1) = 24 divisors.

Frequently asked questions

Is 1 a prime number?

No. By definition a prime has exactly two distinct divisors, and 1 has only one.

Is 2 the only even prime?

Yes. Every other even number is divisible by 2.

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