Fatto generale: 84731 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 84731 is an unremarkable number.
Trivia: 84731 is an uninteresting number.
Data storica: December 26th is the day in 1900 that a relief crew arrives at the lighthouse on the Flannan Isles of Scotland, only to find the previous crew has disappeared without a trace.