Fatto generale: 604 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 604 is an unremarkable number.
Trivia: 604 is a boring number.
Data storica: August 26th is the day in 1278 that Ladislaus IV of Hungary and Rudolph I of Germany defeat Premysl Ottokar II of Bohemia in the Battle of Marchfield near Dürnkrut in (then) Moravia.