The song has sold 13.2 million copies worldwide, becoming one of the best-selling singles of all time and becoming Katy's biggest seller for any song, surpassing Firework which sold 11 million copies worldwide.
The song has sold 13.2 million copies worldwide. The song was becoming one of the best-selling singles of all time. The song was becoming Katy's biggest seller for any song. Any song is surpassing Firework. This Firework sold 11 million copies worldwide.