In mathematical parlance, the prime number 113 is said to be permutable because it remains prime regardless of how the digits are arranged, that is 131 and 311.
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Another example of this is 199, which stays prime at 919 and 991.
The first question this week is which three-digit prime number - that does not contain the digit 1 - remains prime when rearranged to form two other numbers?
If you get that solved quickly, try this much harder question as a bonus problem:
This eleven-digit number looks likely to be prime, but actually it has just two factors. Can you find out what they are?