Step 1: Divide the number into separate digits:
24189 => 2 4 1 8 9
Step 2: Calculate the distance between each digit and the next (the last digit with the first):
2 to 4 = 2
4 to 1 = 3
1 to 8 = 7
8 to 9 = 1
9 to 2 = 7
Step 3: Combine the filters to a string:
2 3 7 1 7 = 23717