invertible prime

An invertible prime is a prime which yields a different prime when the prime is inverted (turned upside down). E.g., 109 becomes 601. It must contain only the digits 0, 1, 6, 8, or 9. Charles W. Trigg (1898-1989) called the pair prime rotative twins.

Printed from the PrimePages <> © Chris Caldwell.