Fatto generale: 637 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 637 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 637 is an unremarkable number.
Data storica: September 28th is the day in 1958 that France ratifies a new Constitution of France; the French Fifth Republic is then formed upon the formal adoption of the new constitution on October 4.