Prime Number Checker
Instantly test whether a number is prime or composite
Positive integers only · Primes: 2, 3, 5, 7, 11, 13, 17, 19, 23...
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What is a Prime Number?
A prime number is a natural number greater than 1 that has exactly two factors: 1 and itself. These numbers cannot be divided evenly by any other number, making them fundamental in mathematics and number theory.
For example, 2, 3, 5, and 7 are prime numbers because they are only divisible by 1 and themselves.