97

This number is a prime.

The setting is 97 years after a devastating nuclear apocalypse wipes out almost all life on Earth. "The 100" are a subgroup of the Sky People and the namesake of the TV series. They are one hundred juvenile delinquents sent to what was formerly Virginia to determine if the planet had become habitable. Consider yourself a prime curiologist if you recognized that 97 is the largest prime number less than 100.