7321

This number is a prime.

+ The smallest zeroless prime whose product of the first two digits is a concatenation of the 3rd and 4th digits. [Gallardo]

+ The smallest emirp that splits into an emirp and the corresponding prime subscript (73 is the 21st prime). [Loungrides]

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

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