Fatto generale: 21195 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21195 is an unremarkable number.
Trivia: 21195 is a boring number.
Data storica: January 10th is the day in 1946 that the United States Army Signal Corps successfully conducts Project Diana, bouncing radio waves off the moon and receiving the reflected signals.