Problem 52639. Determine whether a number is unprimeable

ChrisR

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The number 204 is unprimeable because no single digit can be changed to make it prime. In contrast, the number 207 is not unprimeable because changing the first digit to 0, 1, 3, 6, or 9 or the second digit to 2, 5, or 7 would make it prime. 
Write a function to determine whether the input number is unprimeable. 

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Last Solution submitted on Nov 29, 2025

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