The integers $167$ and $761$ are both prime. In this question, a reversible prime is a prime who

Question

The integers $167$ and $761$ are both prime. In this question, a reversible prime is a prime whose digit reversal is also prime; an unchanged reversal such as $11$ is allowed. The original example $163,361$ is invalid because $361=19^2$. Explain why the prime number $271$ with its digits reversed is not a prime. How many $2$-digit reversible primes can you list?

Accepted Answer

(a) $172$ is even (b) $9$ reversible primes: $11,13,17,31,37,71,73,79,97$

Reversible Primes and Digit Reversal

Reversible Primes and Digit Reversal

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