Step 1: Divide the number into separate digits:
46709 => 4 6 7 0 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
4 to 6 = 2
6 to 7 = 1
7 to 0 = 7
0 to 9 = 9
9 to 4 = 5
Step 3: Combine the filters to a string:
2 1 7 9 5 = 21795