Fait général: 17720 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 17720 is an unremarkable number.
Culture générale: 17720 is an uninteresting number.
Date historique: July 6th is the day in 1893 that the small town of Pomeroy, Iowa, is nearly destroyed by a tornado that kills 71 people and injures 200.