1213

This number is a prime.

+ The smallest four-digit prime (emirp) containing consecutive numbers (12 and 13). [Das]

+ 12 and 13 are relatively prime, while 12^2 + 13^2 = 313 (a palindromic prime). Note also that 12^4 + 13^4 = 49297 is prime. [La Haye]

+ The smallest of eight consecutive emirps. [Punches]

+ The smallest emirp whose product of digits is a perfect number. [Loungrides]

+ The only emirp concatenated from two double-digit numbers that are sides in an equable triangle, i.e., (5, 12, 13). (A shape is called equable if its area equals the perimeter). [Loungrides]

+ Only non-titanic emirp, that is the product of a repunit number and all its truncations minus eight, i.e., 111*11*1-8. [Gupta]

(There are 4 curios for this number that have not yet been approved by an editor.)

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