Fatto matematico: 637 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 637 is an uninteresting number.
Data storica: September 28th is the day in 1973 that the ITT Building in New York City is bombed in protest at ITT's alleged involvement in the September 11, 1973 coup d'état in Chile.