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 ...

After shocking the mathematics community with a major result in 2013, Yitang Zhang now says he has solved an analogue of the celebrated Riemann hypothesis. A mathematician who went from obscurity to ...

The largest known prime number has been discovered by an amateur researcher and former Nvidia employee. The new number is 2 136,279,841 – 1, which beats the previous title holder (2 82,589,933 – 1) by ...