Fatto generale: 1681 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 1681 is a square and each of its two 2-digit parts is square.
Trivia: 1681 is an uninteresting number.
Data storica: August 7th is the day in 1782 that George Washington orders the creation of the Badge of Military Merit to honor soldiers wounded in battle.