121499449

This number is a prime.

The largest prime factor of any 28-digit repdigit. Note that 28 is perfect. [Bowser]

The largest prime (emirp) factor of 10^14+1. [Loungrides]

The largest prime factor, (it is also emirp), of any number formed by repeating seven times any 4-digit number, (prime or composite). [Loungrides]