By Ian Youngs
Music reporter, BBC News
Miley Cyrus is trying to forge a music career after playing a pop star on TV
She is America's biggest teen idol, the star of her own hit TV show and has chart-topping films and albums under her belt.
Miley Cyrus, a megastar at the age of 15, talks about fame, controversy and her future.
The following achievements would be impressive for a seasoned entertainer. For a teenager, they are dazzling, verging on the extreme.
Miley Cyrus is one of the world's 100 most influential people, according to Time magazine, with annual earnings of $25m (£14.5m), according to Forbes.
She has had two albums at number one in the US, a film at the top of the box office, another in the pipeline, and has finished writing her autobiography. Already.
And she has her own merchandise, ranging from branded dolls and clothes to lunchboxes, digital cameras and an inflatable bed.
The star of Disney show Hannah Montana, Cyrus is pursuing a pop career and is one of the most in-demand celebrities in the US.
On screen since 13, and as the daughter of country singer Billy Ray Cyrus, fame is now a way of life for Miley.
In fact, when she was not mobbed by fans or paparazzi in London at the weekend, it came as a shock.
"It's really strange," she says. "I went to Starbucks and there was, like, no-one.
"No-one asked me for my autograph, no-one did anything, so I was like 'woah, this is really cool, this is really strange.'"
Her appeal has travelled across the Atlantic, though, and she played to 5,000 screaming fans on Sunday.
"When I show up at concerts, it's like, chaotic, because I'm never here so it's really a big deal when I finally get to come to the UK."
Cyrus was born in November 1992, four months after her father and his trademark mullet enjoyed a massive hit with Achy Breaky Heart.
"I was born right when Achy Breaky came out, so I missed all that stuff," Miley says.
"But afterwards, I remember him being on tour. He travelled so much, he was gone a lot.
"But that was cool for me, being able to be independent and work my way to acting and singing myself, and not just by following my dad's lead."
She decided at seven or eight she wanted to be a professional singer and actress, starting in school plays before getting a small part in one of her dad's TV shows.
Billy Ray Cyrus plays Miley's father on screen in Hannah Montana
She was credited under her real name Destiny Hope Cyrus for a role in the film Big Fish, starring Ewan McGregor.
Then the big break came and she won the role in Hannah Montana, playing a normal schoolgirl who leads a secret double life as a pop sensation.
The show is pure tween fantasy, and has given her the perfect platform from which to launch an assault on the charts.
A soundtrack album went to number one last year, and her follow-up, Breakout, is meant to be Miley's musical break from the bubblegum pop of her TV persona.
Six weeks from her 16th birthday, Miley talks at times like a Clueless teenager, marvelling at the time difference between the US and UK ("it's really weird") and discussing free time spent "hanging out with my friends and playing with my puppies".
But she also has unswerving confidence, appears unfazed by her fame and answers questions with a businesslike efficiency.
Miley Cyrus recently had a 16th birthday party at Disneyland
Because of her age, she is accompanied everywhere by a tutor, who also shields Cyrus from some of the pressures of stardom.
"Since I'm under 18, I can only work a certain amount of hours, so she's here to make sure that I don't go over time because otherwise I get in trouble," Cyrus says.
"I love that I'm not having to stop in the middle of education to do this. Everyone's like 'But you go to school to get a job, and you already have a job'.
"But I'm like 'You don't know how long this lasts', so it's really nice to have something to fall back on."
Celebrity also means that every slip-up is scrutinised, as Cyrus discovered earlier this year.
A controversy briefly raged after photos for Vanity Fair magazine showed her apparently topless, dishevelled and wrapped in a bedsheet.
Pitfalls of fame
"I'm OK with it because it's settled down, so it's fine and I think it was a really great learning experience for me," she says.
In the coming years, that experience may be valuable as she tries to avoid the pitfalls that have caught out other young stars.
She will also need to adapt her image as she and her fans get older if she wants to keep their favour.
Music is likely to be her focus in future years, although she will continue to act, she says.
"I want to do this for the rest of my life, I love it," she replies when asked about her ambitions.
"So hopefully I'll just be able to expand that, keep travelling, and keep doing more records, and grow as an artist and grow as a person as I do so."
Breakout is out now. Miley Cyrus will be on Sound on BBC Two at 1200 on Saturday.