General fact: 5553 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Mathematical fact: 5553 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 5553 is a boring number.
Historical date: March 15th is the day in 351 that Constantius II elevates his cousin Gallus to Caesar, and puts him in charge of the Eastern part of the Roman Empire.