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 ...

One of my favorite anecdotes about prime numbers concerns Alexander Grothendieck, who was among the most brilliant mathematicians of the 20th century. According to one account, he was once asked to ...

The smallest such number is 561: For any integer b, b561 – b is always a multiple of 561, even though 561 is not prime. Numbers like these were named after the mathematician Robert Carmichael, who is ...

2. 3. 5. 7. 11. 13. 17. And so on. This is far from a comprehensive list of prime numbers—if we were to compile and write out an exhaustive list of all known prime numbers, this would be a truly ...