Fatto generale: 23557 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 23557 is an uninteresting number.
Trivia: 23557 is an uninteresting number.
Data storica: June 29th is the day in 1916 that the Irish Nationalist and British diplomat Sir Roger Casement is sentenced to death for his part in the Easter Rising.