Fatto generale: 2291 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 2291 is the number of inequivalent Ferrers graphs with 29 points.
Trivia: 2291 is an unremarkable number.
Data storica: April 9th is the day in 1992 that John Major's Conservative Party wins an unprecedented fourth general election victory in the United Kingdom.