Fatto generale: 28031 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 28031 is an uninteresting number.
Trivia: 28031 is an uninteresting number.
Data storica: September 28th is the day in 1787 that the newly completed United States Constitution is voted on by the U.S. Congress to be sent to the state legislatures for approval.