"Firework" is her biggest hit, with U.S. sales of 5,869,000 copies. It is followed by "California Gurls" (featuring Snoop Dogg, 5,374,000), "E.T." (featuring Kanye West, 5,361,000) and "Hot N Cold" (5,281,000).
And some people doubt "E.T.", soon to be her second best seller.
She deserves it tbh
Congrats to Katy