9431

This number is a prime.

+ 92 + 42 + 32 + 12 is prime. [Trigg]

+ The largest 4-digit distinct-digit prime whose sum of the repdigit numbers of its digits, self-repeated, is an emirp, i.e., 999999999+333+4444+1 = 1000004777. [Loungrides]

(There is one curio for this number that has not yet been approved by an editor.)

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