The song was written by the three rappers alongside Rico Love, Ivory Scott, S-X, Aaron Ferrucci, Martell Smith Williams, & producers Diego Ave, Bankroll Got It, Chambers, Mally Mall, and Nana Rogues.

In both the chorus and his verse, KSI relishes in his success and addresses those who have hated on him and doubted him in the past, with an auto-tune-heavy delivery.

"Number 2" received generally positive reviews from music critics, with many praising its production and the three rappers' "hard" and "commanding" performances.

The futuristic video alternates between shots of the three rappers playing an online car racing video game in their respective homes and in-game footage of the trio racing through a virtual CGI cityscape, behind the wheels of three matching BMWs.

During his guest appearance on the American talk show The Late Late Show with James Corden on 20 April 2021, KSI exclusively revealed that his upcoming second studio album would include a track that features American rappers Future and 21 Savage, titled "Number 2".

[8] In their verses, Future and 21 Savage flaunt their wealth and lavish lifestyles, with a theme of street level braggadocio.

Williams noted that some of KSI's lyrics are "goofy" and believed that the song is "saved by clean verses from Future and 21 Savage", although she admitted that the pair also "turn in some mediocre bars".

[6] Writing for Earmilk, Chloe Robinson described the instrumental as "bold" and "vibrant" and commended its "fresh, sonic flavour" that has a "masterful, magnetic feel".

[8] In her review for HotNewHipHop, Erika Marie proclaimed that "Number 2" would be "a standout [track] for hip hop fans".

[15] The futuristic video alternates between shots of the three rappers playing an online car racing video game in their respective homes and in-game footage of the trio racing through a virtual CGI cityscape, behind the wheels of three matching BMWs.

[11] At the end of the video, the three rappers appear to hit an unfinished part of the game and drive off a cliff to their demise.