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Check whether a number is prime or composite instantly. Find prime factors, divisors, and prime numbers within a range using this free online prime number calculator.
Enter a positive whole number to check whether it is prime.
Enter several whole numbers separated by commas, spaces, or new lines.
Find all prime numbers between your selected starting and ending values.
A prime number is a whole number greater than 1 that has exactly two positive divisors: 1 and itself. The number 2 is the only even prime number. The number 1 is neither prime nor composite.
For performance, the range finder supports ranges of up to 100,000 numbers at a time. Single-number checks support safe whole numbers up to JavaScript's maximum safe integer.
