15149

This number is a prime.

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15149 is the smallest emirp e initiating a chain of exactly three emirps via the modulus of itself and its reversal. The rule max(e, rev(e)) mod min(e, rev(e)) yields 15149 → 3257 → 1009, terminating at the next step with 929, a palindromic prime. Notably, the only other emirp producing this same chain is 94151 — the reversal of 15149 itself. Furthermore, the reversals of the chain emirps (94151, 7523, and 9001) are the 1451st, 167th, and 191st emirps respectively, and all three of these indices are prime with prime digital roots. [Ahmed]