6174
= 6174
{wiki=6174}
The number 6174 is known as Kaprekar's constant. It is famous in the field of number theory due to a process known as Kaprekar's routine. The process works as follows: 1. Take any four-digit number that has at least two different digits (for example, 3524). 2. Arrange the digits in descending order to get the largest possible number (4325). 3. Arrange the digits in ascending order to get the smallest possible number (2345).