Python function to translate a number to a word

numberToWord.py

def numWords(num): 
  words = ["zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", 
           "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"]
  iwords = ["", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten"]
  twords = ["","teen","twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"]
  myStr = ""
  huns = ""
    

  # if over a thousand, first mod with 1000 to get next lower magnitude
  if (num >= 1000):
    tuns = num / 1000
    num = num % 1000
    myStr += iwords[tuns] + " thousand "
        
  if (num >= 100):
    # if over a hundred, find which hundred via integer division
    huns = num / 100
    myStr += iwords[huns] +  " hundred"
    # now get next lowest magnitude via mod
    num %= 100
    if num > 0:
        myStr += " and "

  if (num >= 20):
    tens = num / 10
    num %= 10
    # add tens words 
    myStr += twords[tens]
    if (num > 0):
        myStr += "-"+words[num]
  elif num > 0:
    myStr += words[num]

  return myStr