invertible prime
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GIMPS has discovered a new largest known prime number: 282589933-1 (24,862,048 digits)

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.

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