I know you didn’t mean this seriously, but it’s easy to see:

• zero has 4 letters
• one has 3 letters
• two has 3 letters
• three has 5 letters
• four has 4 letters
• five has 4 letters
• six has 3 letters
• seven has 5 letters
• eight has 5 letters
• nine has 4 letters
• ten has 3 letters
• eleven has 6 letters
• twelve has 6 letters
• after this, there are no possible candidates anymore: the next numbers are all just 3-9 (with slight spelling variations) followed by 4-letter “teen”, giving us at most 9 letters, too few to have equal value to the numbers they name
• after that there is no possible way to get to the high values of the numbers they name by combining words like “twenty” or “thirty” or “hundred” or “thousand” or “million” with the previous ones