Fatto generale: 2351 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 2351 is a member of the Fibonacci-type sequence starting with 2 and 5.
Trivia: 2351 is an unremarkable number.
Data storica: June 8th is the day in 1953 that the United States Supreme Court rules that Washington, D.C. restaurants could not refuse to serve black patrons.