Fatto generale: 873 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 873 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 873 is an uninteresting number.
Data storica: May 22nd is the day in 1942 that the Steel Workers Organizing Committee disbands, and a new trade union, the United Steelworkers, is formed.