Step 1: Divide the number into separate digits:
31619 => 3 1 6 1 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
3 to 1 = 2
1 to 6 = 5
6 to 1 = 5
1 to 9 = 8
9 to 3 = 6
Step 3: Combine the filters to a string:
2 5 5 8 6 = 25586