Mathematical fact: 7800 is the order of a non-cyclic simple group.
Trivia: 7800 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Historical date: May 9th is the day in 2004 that Chechen president Akhmad Kadyrov is killed by a land mine under a VIP stage during a World War II memorial victory parade in Grozny, Chechnya.