Step 1: Divide the number into separate digits:
25971 => 2 5 9 7 1
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 5 = 3
5 to 9 = 4
9 to 7 = 2
7 to 1 = 6
1 to 2 = 1
Step 3: Combine the filters to a string:
3 4 2 6 1 = 34261