Hecho general: 2391 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 2391 is the number of ways to flip a coin 12 times and get at least 3 heads in a row.
Trivia: 2391 is an unremarkable number.
Fecha histórica: July 18th is the day in 1986 that a tornado is broadcast live on KARE television in Minnesota when the station's helicopter pilot makes a chance encounter.