There is about 78 but heaps more if you start considering words derived from other languages. I read a lot and I find that you often don't even notice that you have a read a sentence containing a heteronym.
There are more than 100,000,000 words in the English language.The previous answer is incorrect. No language has more than a million words. The real answer is that it has less than 250,000 words, but...
An interesting question though I think there would be too many to count. Every colony they had, had influence their language. Then there are the countries in Europe and they have all had words from...