Mathematical fact: 1287 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 1287 is an unremarkable number.
Historical date: July 10th is the day in 1850 that Millard Fillmore is inaugurated as the 13th President of the United States upon the death of President Zachary Taylor, 16 months into his term.