Fatto generale: 556 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 556 is an uninteresting number.
Trivia: 556 is an uninteresting number.
Data storica: July 9th is the day in 1793 that the Act Against Slavery is passed in Upper Canada and the importation of slaves into Lower Canada is prohibited.