If you're talking about the year, you say twenty-one-twenty. As a number, like a quantity of money, that may also work, but you're more likely to say two thousand one hundred twenty. For 32,120, I'm afraid you're stuck with the long form. If it were 32,500, you could say thirty two thousand five, or thirty two and a half thousand. People also use 'K' to mean thousand, i.e. thirty two and a half K.