Reverse divisible number
In number theory, reversing the digits of a number sometimes produces another number that is divisible by.
This happens trivially when is a palindromic number; the nontrivial decimal reverse divisors are
For instance, 1089 × 9 = 9801, the reversal of 1089, and 2178 × 4 = 8712, the reversal of 2178.
The multiples produced by reversing these numbers, such as 9801 or 8712, are sometimes called palintiples.
Properties
Every nontrivial decimal reverse divisor must be either 1/4 or 1/9 of its reversal.The number of -digit nontrivial reverse divisors is where denotes the th Fibonacci number.
For instance, there are two four-digit reverse divisors, matching the formula.