1091

This number is a prime.

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The smallest Honaker emirp. Note that its next Honaker prime (1301) is also an emirp and the concatenation of these two emirps (13011091) is prime as well. [Loungrides]

The only known invertible emirp of form (x^3+y^3+z^3)/(x+y+z), where x, y, z are consecutive numbers (case x=32), i.e., 1091=(32^3+33^3+34^3)/(32+33+34). [Loungrides]

The smaller prime (emirp) in the first pair of invertible primes, (1091, 1601), whose concatenation, i.e., 10911601, is a strobogrammatic prime. [Loungrides]