85
This number is a composite.
(8511 - 85)/11 ± 1 are twin primes. [Luhn]
Between 641 and 114689 (the second smallest Fermat divisor) there exist 85 prime numbers that could conceivably be Fermat divisors.
There are 85 five-digit primes that begin with 85. [Bopardikar]
The only composite number resulting from the sum of three double-digit consecutive emirps, 17, 31, 37. Note that the ordered concatenation of these emirps, i.e., 173137 is prime. [Loungrides]
The only known Smith number n such that the aliquot sum of n = π(n). [Gupta]
(There is one curio for this number that has not yet been approved by an editor.)
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