Prime numbers are tricky things. We learn in school that they’re numbers with no factors other than 1 and themselves, and that mathematicians have known for thousands of years that an infinite number ...

A basic feature of number theory, prime numbers are also a fundamental building block of computer science, from hashtables to cryptography. Everyone knows that a prime number is one that cannot be ...

The online computer game “Is this prime?” tests a player’s knowledge of prime numbers—and just surpassed 2,999,999 attempts. Give it a whirl. The Greek mathematician Euclid may very well have proved, ...