Largest prime number discovered has over 22 million digits
The largest known prime number, comprising more than 22 million digits, was discovered using a computer in early 2016 in Missouri, US. The number, whose value is  calculated as '2 raised to 74,207,281 minus 1', is five million digits longer than the previous largest known prime number. Prime numbers are those numbers which are divisible only by themselves and 1. 