Fatto generale: 5500 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 5500 is an uninteresting number.
Trivia: 5500 is a boring number.
Data storica: January 21st is the day in 1968 that a B-52 bomber crashes near Thule Air Base, contaminating the area after its nuclear payload ruptures.