Fatto generale: 90423 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 90423 is an unremarkable number.
Trivia: 90423 is an uninteresting number.
Data storica: July 27th is the day in 1919 that the Chicago Race Riot erupts after a racial incident occurred on a South Side beach, leading to 38 fatalities and 537 injuries over a five-day period.