11 to iu na no Eien no Sosou

11 to iu na no Eien no Sosou (11という名の永遠の素数 lit. An eternal prime number named 11.) is the first album by 22/7. It was originally scheduled to be released on June 30, 2021, but had been delayed to July 14, 2021.

Tracklist
Note: Tracks in bold represent new songs within the album.

Featured Members

 * Nagomi Saijo as Miu Takigawa
 * Sally Amaki as Sakura Fujima
 * Mizuha Kuraoka as Miyako Kono
 * Chiharu Hokaze as Reika Sato
 * Ruri Umino as Jun Toda
 * Kanae Shirosawa as Akane Maruyama
 * Reina Miyase as Ayaka Tachikawa
 * Mei Hanakawa as Nicole Saito
 * Uta Kawase as Nicole Saito
 * Moe Suzuhana as Mikami Kamiki
 * Urara Takatsuji as Yuki Tojo
 * Aina Takeda as Tsubomi Hiiragi

Trivia

 * Despite the album revolving around the importance of having 11 members in the group, the exclusive songs released in the album are only sung by 10.
 * This was due to Chiharu Hokaze's graduation from the group earlier in the year.