Fatto generale: 8669 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 8669 is the maximum value of n so that there exist 5 denominations of stamps so that every postage from 1 to n can be paid for with at most 18 stamps.
Trivia: 8669 is a boring number.
Data storica: September 25th is the day in 1912 that Columbia University Graduate School of Journalism is founded in New York, New York.