Fatto generale: 6304 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 6304 is a boring number.
Trivia: 6304 is an uninteresting number.
Data storica: April 4th is the day in 1913 that the Greek aviator Emmanouil Argyropoulos becomes the first pilot victim of the Hellenic Air Force when his plane crashes.