The highest known prime number so far has been calculated, and it is much, much larger than the previous prime number that was known. Almost 5 million digits larger. The previous highest prime number was found out to be one subtracted from 2 to the power of 57885161 on the 25th of January 2013. It was calculated by the Great Internet Mersenne Prime Search (GIMPS) and the number had 17,425,170 digits.