Fatto generale: 251 is the last and most powerful prime mover (engine) designed and built by the American Locomotive Company (ALCO).
Fatto matematico: 251 is also sum of three consecutive primes (79 + 83 + 89) and sum of seven consecutive primes (23 + 29 + 31 + 37 + 41 + 43 + 47).
Trivia: 251 is the number of Pokémon available in Pokémon Gold and Silver is 251.
Data storica: September 7th is the day in 1979 that the Chrysler Corporation asks the United States government for USD $1.5 billion to avoid bankruptcy.