Mathematical fact: 6511 is a number n whose sum of the factorials of its digits is equal to p(n).
Trivia: 6511 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Historical date: October 28th is the day in 1929 that Black Monday, a day in the Wall Street Crash of 1929, which also saw major stock market upheaval.