Step 1: Divide the number into separate digits:
25939 => 2 5 9 3 9
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 3 = 6
3 to 9 = 6
9 to 2 = 7
Step 3: Combine the filters to a string:
3 4 6 6 7 = 34667