Fatto generale: 15809 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 15809 is an unremarkable number.
Trivia: 15809 is an unremarkable number.
Data storica: April 13th is the day in 1919 that Eugene V. Debs enters prison at the Atlanta Federal Penitentiary in Atlanta, Georgia, for speaking out against the draft during World War I.