Hecho matemático: 8217 is a centered icosahedral number.
Trivia: 8217 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fecha histórica: June 30th is the day in 1971 that Ohio ratifies the 26th Amendment to the U.S. Constitution, reducing the voting age to 18, thereby putting the amendment into effect.