General fact: 6209 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 6209 is an unremarkable number.
Trivia: 6209 is an unremarkable number.
Historical date: December 30th is the day in 1816 that the Treaty of St. Louis (1816) between the United States and the united Ottawa, Ojibwa, and Potawatomi Indian tribes is proclaimed.