This number is a prime.
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The smallest palindromic prime using two distinct digits which when interchanged forms another palindromic prime (313). Note that in both cases a new palindromic prime with a prime number of digits is generated when each digit d is repeated d times: 13331; 3331333. [Beedassy]
The smallest Honaker prime, i.e., 131 = P32, and 1 + 3 + 1 = 3 + 2. Note that the latter sum of digits corresponds to the smallest prime with prime subscript (3 = P2) added to its very (prime) subscript. [Beedassy]