73

This number is a prime.

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73 is the only Sheldon prime, i.e., i) whose binary representation is palindromic (10010012) and ii) which belongs to an emirp pair (Pn, Pm) such that subscripts (m, n) = (21, 12) are also reversals of each other and n has a prime decomposition 21 = 3*7 that concatenates back to Pm (Carl Pomerance, Chris Spicer, February 2019). [Beedassy]

Submitted: 2019-04-18 12:18:11;   Last Modified: 2019-04-18 13:04:41.
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