On 08/02/2013 19:31, Nick wrote:
Because (large) prime numbers are used in all encryption systems. These
systems rely for security on no-one being able to predict where to find
'new' or existing primes. If someone has worked out how to do it, they
won't shout about it because they'll be in control of everybody else's
private information.

It likely is the largest one identified. If someone has found a fast way
to factor large numbers they won't be interested in numbers bigger than
encryption keys - so only a hundred or so digits.

Andy