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.

A prime number is a whole number that can only be divided by 1 and itself. A former Nvidia programmer discovered the world's largest known prime number using graphics processing units.

Luke Durant, a researcher and amateur mathematician, has identified the largest new prime number known to humankind. The newly discovered prime number is 2 to the power of 136,279,841, then minus one.

Now, Luke Durant, a 36-year-old researcher and former employee of tech giant NVIDIA, has discovered the 52nd Mersenne prime, which also happens to be the largest prime number known to ...