Twenty is the number that is after nineteen and before twenty-one.
t w ɛ n t i WORD_BOUNDARY ɪ z WORD_BOUNDARY ð ə WORD_BOUNDARY n ʌ m b ə ɹ WORD_BOUNDARY ð æ t WORD_BOUNDARY ɪ z WORD_BOUNDARY æ f t ə ɹ WORD_BOUNDARY n aɪ n t iː n WORD_BOUNDARY æ n d WORD_BOUNDARY b ɪ f ɔ ɹ WORD_BOUNDARY t w ɛ n t i w ʌ n WORD_BOUNDARY