You need hyphens between the numbers (no spaces)
20 - twenty
21 - twenty-one
22 - twenty-two
23 - twenty-three
30 - thirty
33 - thirty-three
34 - thirty-four
40 - forty (drop the 'u' four - fourteen - forty)
44 - forty-four
45 - forty-five
50 - fifty (five - fifteen - fifty)
55 - fifty-five
56 - fifty-six
60 - sixty
66 - sixty-six
67 - sixty-seven
70 - seventy
77 - seventy-seven
78 - seventy-eight
80 - eighty
88 - eighty-eight
89 - eighty-nine
90 - ninety
99 - ninety-nine
100 - a hundred/one hundred
121 - one hundred and twenty-one
453 - four hundred and fifty-three