After 2000 years of searching we only know of 51 perfect numbers and they're all even. What else do and don't we know about these rare and precious jewels of maths?
A new prime number with nearly 25 million digits was discovered just in time for Christmas.
Prime number enthusiasts discover new largest prime with 22,338,618 digits.
They've done it again! GIMPS has discovered the largest known prime number: 257,885,161-1. This massive 17,425,170 digit number was discovered thanks to clever distributed computing software that uses idle computer time donated by volunteers.