Fatto generale: 4023 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 4023 is the number of ways to tile a 3×23 rectangle with 3×1 rectangles.
Trivia: 4023 is an unremarkable number.
Data storica: January 5th is the day in 1066 that Edward the Confessor dies childless, sparking a succession crisis that will eventually lead to the Norman conquest of England.