Create a function that counts the number of digits in a number. Conversion of the number to a string is not allowed, thus, the approach is either recursive or iterative.
digits_count(4666) ➞ 4
digits_count(544) ➞ 3
digits_count(121317) ➞ 6
digits_count(0) ➞ 1
digits_count(12345) ➞ 5
digits_count(1289396387328) ➞ 13