Fatto generale: 2820 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 2820 is an unremarkable number.
Trivia: 2820 is an unremarkable number.
Data storica: September 20th is the day in 1962 that James Meredith, an African-American, is temporarily barred from entering the University of Mississippi.