Katy Perry and Rihanna are close friends, and now they're close on the Billboard chart as well.  Katy has just tied Rihanna's record for the most #1 hits on the publication's Pop Songs chart, which has been around for 20 years.

Katy's latest hit "Wide Awake" has just topped the Pop Songs chart, giving her her ninth #1.  Rihanna has already had nine chart-toppers on that survey.  Impressively, Katy managed to rack up all her #1s in just four years.  Rihanna did it in seven years.

After Katy and Rihanna, the other artists with the most #1s on that chart are Lady Gaga , Pink and Britney Spears , each of whom have seven, and Beyonce and Mariah Carey , who have six each.

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