Fatto generale: 11609 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 11609 is a boring number.
Trivia: 11609 is a boring number.
Data storica: October 13th is the day in 1892 that Edward Emerson Barnard discovers D/1892 T1, the first comet discovered by photographic means, on the night of October 13–14.