6666666666
This number is a composite.
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The only 10-digit rep-digit number such that the sum of itself and all of its truncations plus one is prime, i.e.,
6666666666+666666666+66666666+6666666+666666+66666+6666+666+66+6+1=7407407401. [Loungrides]
Submitted: 2015-06-14 07:35:01; Last Modified: 2018-04-24 10:46:19.
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