6173

This number is a prime.

+ Delete any digit of 6173 and it will remain prime. [Blanchette]

+ The prime 6173 stays prime if any digit is deleted, and its sum of digits is the prime in its middle. [Post]

+ The largest prime formed by concatenating two consecutive double-digit Pythagorean primes. (A Pythagorean prime is a prime number of the form 4n + 1). [Loungrides]

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