General fact: 556 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 556 is an uninteresting number.
Trivia: 556 is an unremarkable number.
Historical date: July 9th is the day in 1776 that George Washington ordered the Declaration of Independence to be read out loud to members of the Continental Army in New York City for the first time.