(Courtesy Teen Vogue)

Justin Bieber has nearly 37 million Twitter followers, but, according to the pop star, offline, he's actually sort of a loner.

In the May issue of Teen Vogue, on stands April 15, the 19-year-old pop star opens up about how fame has made him more cautious about getting close to people.

"Literally, my phone never rings," he says. "I only have, like, four people that I keep in contact with. I don't need a bunch of close friends to make me happy."

Instead, Bieber relies on his fans for support, as well as his parents and best friend, rapper Lil' Twist, whom some have accused of being a bad influence.

"When I first got signed, I moved to Atlanta and met Twist," he explains. "The funny thing is, I was nobody when we were hanging out. Twist knows me for me."

And following a very public split from girlfriend Selena Gomez, as well as a recent confrontation with his neighbor, he'll be leaning on his loved ones more than ever as he prepares for a world tour and deals with global fame.

"When people get to where they want, they're like, 'I'm here, I got it,'" he says. "When I get to the top, I just want to get better."