Fait mathématique: 20123 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Culture générale: 20123 is a boring number.
Date historique: February 3rd is the day in 1918 that the Twin Peaks Tunnel in San Francisco, California begins service as the longest streetcar tunnel in the world at 11,920 feet (3,633 meters) long.