Fatto matematico: 6489 is half again as large as the sum of its proper divisors.
Trivia: 6489 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: October 6th is the day in 1600 that Jacopo Peri's Euridice, the earliest surviving opera, receives its première performance in Florence, signifying the beginning of the Baroque Period.