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A 20 millionth "Little Monster," as Lady Gaga calls her fans, signed up to follow her Twitter feed over the weekend.
She had 20.12 million followers as of Monday for her @ladygaga account.
Teen pop idol Justin Bieber was next with 18.11 million followers of his @justinbieber feed.
Rounding out the top five were three other singers: Katy Perry with 15.75 million followers, Shakira with 14.56 million and Rihanna with 14.49 million.
US President Barack Obama was in eighth place with 12.84 million followers of his @barackobama account.