113173

This number is a prime.

+ The smallest 6-digit prime such that any substring of length 2 or 3 (for you know 6 factors into 2 * 3, hence the 2- & 3-digit substrings) yields only distinct primes (11, 13, 31, 17, 73, 113, 131, 317, 173). [De Geest]

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