Fatto generale: 20643 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 20643 is an unremarkable number.
Trivia: 20643 is an unremarkable number.
Data storica: July 7th is the day in 1981 that U.S. President Ronald Reagan appoints Sandra Day O'Connor to become the first female member of the Supreme Court of the United States.