Computer breaks world-record for prime number

The world's largest prime, a number that can only be divided by 1 and itself, has been uncovered by a computer in Missouri. The 22 million digit number has smashed the previous record-holder by 5 million digits. The number is 2^74,207,281-1, the largest ever seen. In addition to its rules of division, the other special characteristic, is that they can also be used in computer cryptography as security keys.