215

This number is a composite.

+ There are a palindromic prime number of elements, 101 to be exact, in the Hailstone (or 3x+1) sequence of this number. [Patterson]

+ The smallest composite number whose the product with its reversal plus 1, is a 2-sphenic number, i.e., 215*512+1= 110081 = 31 × 53 × 67. Note that two of the concatenations of its prime factors are primes and another is equal to a 4-almost prime with double-digit primes, i.e., 536731 = 13 × 19 × 41 × 53. [Loungrides]

Printed from the PrimePages <primes.utm.edu> © G. L. Honaker and Chris K. Caldwell