Fait général: 21938 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fait mathématique: 21938 is an unremarkable number.
Culture générale: 21938 is an uninteresting number.
Date historique: January 23rd is the day in 1964 that the 24th Amendment to the United States Constitution, prohibiting the use of poll taxes in national elections, is ratified.