This may be the only kanji with a six-mora reading, of uketamawari. However, this reading is more often spelled with the final -ri spelled in kana (as 承り) to clarify and disambiguate the reading of the single kanji.
This kanji is also one of very few kanji with five-mora readings, and the only verb, namely 承る (uketamawaru, with the kanji comprising the five-mora uketamawa- part). Other kanji with five-mora readings are the nouns 志 (kokorozashi), 詔 / 勅 (mikotonori), and 宰 / 司 (mikotomochi). No kanji have a reading of more than six morae.