Fatto generale: 5871 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 5871 is a boring number.
Trivia: 5871 is an unremarkable number.
Data storica: January 27th is the day in 447 that the Walls of Constantinople are severely damaged by an earthquake, destroying large parts of the wall, including 57 towers.