Fatto generale: 28000 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 28000 is an uninteresting number.
Trivia: 28000 is an unremarkable number.
Data storica: August 28th is the day in 475 that the Roman general Orestes forces western Roman Emperor Julius Nepos to flee his capital city, Ravenna.