Fatto generale: 20818 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20818 is an uninteresting number.
Trivia: 20818 is a boring number.
Data storica: December 29th is the day in 1835 that the Treaty of New Echota is signed, ceding all the lands of the Cherokee east of the Mississippi River to the United States.