Hecho general: 2129 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 2129 is a boring number.
Trivia: 2129 is an unremarkable number.
Fecha histórica: October 29th is the day in 312 that Constantine the Great enters Rome after his victory at the Milvian Bridge, stages a grand adventus in the city, and is met with popular jubilation.