Hecho matemático: 8521 is a prime that is the average of two 4^{th} powers.
Trivia: 8521 is an uninteresting number.
Fecha histórica: April 30th is the day in 1863 that a 65-man French Foreign Legion infantry patrol fought a force of nearly 2,000 Mexican soldiers to nearly the last man in Hacienda Camarón, Mexico.