112131323
This number is a prime.
The prime 112131323 is the concatenation of 1, 1, 2, 1, 3,
1, 3, 2, 3; which is the number of prime factors of
Mersenne number M(n) = 2^n - 1 from n = 2 to n = 10
(counted with multiplicity), or from n+1 to 10 if we allow
a left-most digit of 0. [Post]
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