Fatto generale: 2781 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 2781 is an unremarkable number.
Trivia: 2781 is a boring number.
Data storica: August 12th is the day in 1964 that Charlie Wilson, one of the Great Train Robbers, escapes from Winson Green Prison in Birmingham, England.