222

This number is a composite.

+ The number 2222 + 22222 + 222222 + 1 is prime. [Patterson]

+ 222 is the smallest repdigit such that the product of itself and all truncations of itself plus and minus one results in twin primes. I.e., 222*22*2 ± 1 are twin primes. [Opao]

+ 222 is the sum of all 2-digit primes formed from consecutive digits. [Silva]

+ 109 and 113 are the smallest pair of consecutive primes with a repdigit sum (222). The next such pair are 4441 and 4447. [Gaydos]

+ The sum of two emirp pairs plus 2 is a repunit, i.e., 37 + 37 + 2 + 73 +73 = 222. [Wiszowaty]

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

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