A subprime number is a number which is exactly one less than a prime number. There are an infinite number of subprime numbers, as was indirectly proven by Euclid in the year 300 B.C.E.
1 is a subprime number, because 2 is a prime number, and 2 - 1 = 1. 498 is a subprime number, because 499 is a prime number, and 499 - 1 = 498.
by Lirrad April 13, 2009