1248168421

This number is a prime.

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The first term of the non-palindromic elements of the sequence 1, 121, 12421, 1248421, 1248168421, 12481632168421, ... (Where the k-th number is the concatenation of 2^0, 2^1, ... , 2^(k-1), 2^k, 2^(k-1), ... , 2^1, 2^0) is a prime number. [Leonardis]