Fait mathématique: 2517 is the number of regions the complex plane is cut into by drawing lines between all pairs of 17^{th} roots of unity.
Culture générale: 2517 is an uninteresting number.
Date historique: November 21st is the day in 1969 that U.S. President Richard Nixon and Japanese Premier Eisaku Sato agree in Washington, D.C. on the return of Okinawa to Japanese control in 1972.