Fatto generale: 20411 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20411 is a boring number.
Trivia: 20411 is an unremarkable number.
Data storica: November 18th is the day in 1970 that U.S. President Richard Nixon asks the U.S. Congress for $155 million USD in supplemental aid for the Cambodian government.