Fatto generale: 21867 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21867 is a boring number.
Trivia: 21867 is a boring number.
Data storica: November 13th is the day in 1927 that the Holland Tunnel opens to traffic as the first Hudson River vehicle tunnel linking New Jersey to New York City.