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Prime Number Checker

Check whether a whole number is prime, list its prime factorization, and find the next prime number after it.

About Prime Number Checker

A prime number is a whole number greater than 1 that is divisible only by 1 and itself. This checker uses trial division: it divides the number by 2 and then by each odd number up to its square root, collecting every factor found. If the only factor is the number itself, it is prime. It also searches upward for the next prime. Input is limited to whole numbers from 0 to 100 trillion.

How to use Prime Number Checker

  1. Fill in "Whole number".
  2. The result appears below and updates as you type.
  3. Copy the result with the copy button, or download it as a file where that is offered.

Questions about Prime Number Checker

Is 1 a prime number?

No. A prime must have exactly two distinct divisors, 1 and itself, and 1 has only one. The smallest prime is 2, which is also the only even prime.

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