Convert Positive Integers between 0 and 2^31-1 to English words

from typing import List

def numberToWords(num: int) -> str:

#         Shortcut return if zero:
  if num == 0:
    return "Zero"

# Use divmod to parse number into chunks
  chunks = numberSplitter(num, 1000)

  ordinals = ['Billion', 'Million', 'Thousand', '']
  words = []
  for chunk in chunks:
    # convert chunk into words, add appropriate ordinal
    words.append(hundredUnitToWords(chunk, ordinals.pop()))

  numberWords = ""
  for word in reversed(words):
    if word:
      numberWords += f" {word}"

  return numberWords.strip()

def hundredUnitToWords(num: int, ordinal: str) -> str:
  hundreds, remainder = divmod(num, 100)

  digits = {0: "", 1: "One", 2: "Two", 3: "Three", 4: "Four", 5: "Five", 6: "Six", 7: "Seven", 8: "Eight", 9: "Nine", 10: "Ten", 11: "Eleven", 12: "Twelve", 13: "Thirteen", 14: "Fourteen", 15: "Fifteen", 16: "Sixteen", 17: "Seventeen", 18: "Eighteen", 19: "Nineteen"}
  tens = {0: "", 2: "Twenty", 3: "Thirty", 4: "Forty", 5: "Fifty", 6: "Sixty", 7: "Seventy", 8: "Eighty", 9: "Ninety"}
  hundred = "Hundred"
#         Compose number within 3 digit block

  words = ""
  if hundreds:
    words += f"{digits[hundreds]} {hundred}"
  if remainder:
    # Fix spacing:
    if hundreds:
      words += " "

    if remainder < 20:
#               Special case for numbers less than 20 to cover teens
      words += digits[remainder]
    else:
      #  get 10s portion, add units portion
      ten, one = divmod(remainder, 10)
      words += f"{tens[ten]}{'' if (ten == 0 or one == 0) else '-'}{digits[one]}"
  if words:
    words += f" {ordinal}"

  return words


# Splits a positive integer in groups specified by split, returns them in least to most significant order
def numberSplitter(num: int, split: int) -> List[int]:
    splits = []
    while num > 0:
        sub = divmod(num, split)
        splits.append(sub[1])
        num = sub[0]

    return splits