Find the largest prime divisor of 11! + 12! + 13!.
11! + 12! +13! ==6,745,939,200
6745939200 = 2^8 * 3^4 * 5^2 * 7 * 11 * 13^2
The largest prime divisor ==13
11! + 12! + 13!
=11!(1+12+12*13)
=11!*169
=11! * 13 *13
so yes the largest prime is 13
