Fatto generale: 624 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 624 is the smallest number with the property that its first 5 multiples contain the digit 2.
Trivia: 624 is an uninteresting number.
Data storica: September 15th is the day in 1962 that the Soviet ship Poltava heads toward Cuba, one of the events that sets into motion the Cuban Missile Crisis.