Fatto matematico: 6403 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 6403 is an uninteresting number.
Data storica: July 12th is the day in 1970 that a fire consumes the wooden home of Norwegian composer Geirr Tveitt and irretrievably destroys about 90 percent of his output.