Step 1: Divide the number into separate digits:
64650 => 6 4 6 5 0
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
6 to 4 = 2
4 to 6 = 2
6 to 5 = 1
5 to 0 = 5
0 to 6 = 6
Step 3: Combine the filters to a string:
2 2 1 5 6 = 22156