Fatto generale: 21128 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21128 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 21128 is an uninteresting number.
Data storica: November 4th is the day in 1501 that Catherine of Aragon (later Henry VIII's first wife) meets Arthur Tudor, Henry VIII's older brother – they would later marry.