According to Official Guinness Records,
The longest officially released song is "The Rise and Fall of Bossanova (A 13:23:32 song)" by PC III (USA) which lasts 13 hr 23 min 32 sec, released on 1 November 2016.Michael and Kelley Bostwick beat the current record by more than 10 hours to regain their title.
For a complete list of 2016 records, please visit 2016 Guinness Records in United States.