General fact: 28684 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 28684 is an unremarkable number.
Trivia: 28684 is an uninteresting number.
Historical date: July 13th is the day in 1174 that William I of Scotland, a key rebel in the Revolt of 1173–1174, is captured at Alnwick by forces loyal to Henry II of England.