MTV reports the singer is very active on the social networking site, often sending out messages to her followers to update them on the latest happenings in her career as well as her life. In addition to people following her, she also follows 419,988 people and has sent out 1,102 tweets since joining Twitter.
Currently, Spears is on her Femme Fatale Tour in Europe and has been posting updates on her Twitter of where she will be, and after every show she has been tweeting back to her fans who have posted on her page saying how much they enjoyed her performance.
Spears joins a list that includes Lady Gaga, Justin Bieber, Katy Perry, President Obama and Kim Kardashian, who have all hit the 10 million mark before her.
Shakira may hit the milestone mark next, according to E! Online. The Latin singer currently has 9,229,283 followers on the site.
