Fatto generale: 97 is the number of leap days that the Gregorian calendar contains in its cycle of 400 years.
Fatto matematico: 97 is the 25th prime number (the largest two-digit prime number in base 10), following 89 and preceding 101.
Trivia: 97 is the number of minutes it takes the Hubble space telescope to complete an orbit around the Earth.
Data storica: April 6th is the day in 1866 that the Grand Army of the Republic, an American patriotic organization composed of Union veterans of the American Civil War, is founded.