Big news for big numbers. There’s a new entry in the Largest Known Primes Database, a list of numbers divisible only by one and themselves. At nine million digits long, 10223 × 2 31172165 + 1 comes in ...

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 ...