Hecho matemático: 91451 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 91451 is an uninteresting number.
Fecha histórica: May 20th is the day in 1497 that John Cabot sets sail from Bristol, England, on his ship Matthew looking for a route to the west (other documents give a May 2 date).