Fatto generale: 6309 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 6309 is the closest integer to 25^{e}.
Trivia: 6309 is an unremarkable number.
Data storica: April 9th is the day in 1585 that the expedition organised by Sir Walter Raleigh departs England for Roanoke Island (now in North Carolina) to establish the Roanoke Colony.