Fatto matematico: 8469 is a value of n for which 2n and 3n together use each digit exactly once.
Trivia: 8469 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Data storica: March 9th is the day in 1945 that the Bombing of Tokyo by the United States Army Air Forces began, one of the most destructive bombing raids in history.