21os Akatallilos (Greek: 21ος Ακατάλληλος) (English: 21 X-Rated) is the eighth studio album by Greek pop sensation Sakis Rouvas and his second produced by Vangelis Yannopoulos, for Minos Emi. The album was released on April 9, 2000 in Greece and Cyprus, and debut at number one on the charts. As opposite to his former release Kati apo mena, there is no composition or any contribution by George Theofanous. Main composer was Stratos Diamandis and these songs were his first ever released. A tough bet taken by Sakis' producer, Vangelis Yannopoulos. Other remarkable contributions were the ones of two cult Greek bands Maskes and Ammos, plus the lyrics written by Greek actor star, Lakis Lazopoulos, and Greek lyricist Aris Davarakis. This album was Rouvas' fastest selling album ever since the beginning of his career. The dramatic instrumental introduction part of "Andexa" featured, for many years, as the musical motto of all his live appearances. On track 6 "Stin mama sou", backing vocals are provided by his then manager Elias Psinakis and his then producer Vangelis Yannopoulos, by composer Stratos Diamandis and by other fellows who happened to be present at that moment in the studio premisces... and were invited within the vocal booth.
21os Akatallilos was re-released with two bonus songs in February 2001. The album contains a bonus "Club Mix" of singles "Andexa" and an "Added Mix" of the power-ballad "Se Thelo San Trelos".