129-digit number


This number is better-known as RSA-129.

It was posted in a 1977 magazine article as a challenge.

The co-inventors of RSA Cryptography wanted to see just how hard it was to factorize a number (it was crucial to the new technology).

RSA-129 is created by multiplying two very large prime numbers.

Ron Rivest (the R in RSA) thought it would take 40 quadrillion years for the prime numbers to be found.

He was wrong. It took 17 years.

Watch the Numberphile video to learn more.

I also recommend the extra footage at Numberphile2, which is some extra questions I asked Professor Rivest.