Fatto generale: 6861 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 6861 is a value of n for which s(n-1) + s(n+1) = s(2n).
Trivia: 6861 is a boring number.
Data storica: October 13th is the day in 1992 that an Antonov An-124 operated by Antonov Airlines registered SSSR-82002, crashes near Kiev, Ukraine killing 8.