prime number

noun2

1. •
   Any natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers.

   • The fundamental theorem of arithmetic states that every natural number greater than 1 can be factorized into prime numbers in a way that is unique up to the order in which the factors are written.
2. •
   (no longer used) Any natural number (including 1) that is divisible only by itself and 1.