Sibling sensations

Quiet time is a rarity for the Jonas Brothers these days.

Following a special performance for more than 500 screaming ’tween and teen girls at Apple’s downtown Manhattan store, the brothers – Kevin, 20, Joe, 18, and Nick, 15 – huddled in a stairwell, trying to find a quiet space to conduct an interview.

Good luck with that.

Even as they spoke, their words were almost drowned out by deafening, doglike shrieks from girls still trying to find a way to get at their idols, who have set off a boy-band pop craze not seen since the lofty days of ’N Sync and the Backstreet Boys.

“You kind of either just look around and laugh, or just, like, enjoy it,” Joe, the band’s lead singer, says of the frenzy.

“We’re in awe. … It’s a whirlwind, and we’re happy to be on the ride.”

The fandemonium for the Jonas Brothers reached a fever pitch with the release of their third CD, “A Little Bit Longer.”

It sold more than 525,000 copies in its first week to debut at the top of this week’s Billboard Top 200 album chart – the third-biggest debut of the year, behind Lil Wayne and Coldplay.

With all the hoopla surrounding the new release, the Jonas Brothers’ self-titled second album, released last year, also vaulted into the Top 10. In addition, they are featured on the “Camp Rock” soundtrack, which is at No. 8.

“We are just really living the dream right now,” Kevin says. “For us, having this album finally hit stores and having them sing the songs, knowing that they can actually hear them and have it in their possession is the most amazing thing for us. We’re so excited.”

When the Jonas Brothers released their first CD two years ago, it barely made a blip on the pop scene. But thanks to a tour with Miley Cyrus on her “Hannah Montana/Miley Cyrus: Best of Both Worlds” tour last fall, the brothers have become bona fide superstars, matching the teen queen on the path to world domination.

Their three-night, sold-out stint at Madison Square Garden was also the site of filming for their upcoming 3-D concert flick, following in Cyrus’ footsteps.

They co-starred with up-and-comer Demi Lovato (who also opens for them on their tour) in the Disney Channel movie “Camp Rock.”

They recently signed a multimillion dollar, two-year pact with concert promoter Live Nation, Rolling Stone magazine put them on its cover, and they will be one of the headline performers at next month’s MTV Video Music Awards.

Kevin credits their popularity explosion to the diligence of their fans.

“They, really in the last year, kicked into high gear with coming to the shows, following the music and continuing to talk about it online,” he says.

“The online thing has been really big for us: the YouTube videos, the MySpace … all of that. But for us, all of them outside make it all possible.”

Outside the Apple store, there was a line of 1,000-plus screaming fans – some of whom waited for two days – singing Jonas songs in unison and braving a sudden downpour for the chance to see the brothers, though only about 500 got inside to see them up close (including Harry Connick Jr. and his daughter).

“We’ve been here since Monday afternoon at 12, so we’ve been camping out all night and it was so cold when it hit 3 a.m.,” said Priscilla Huang, 17, of Brooklyn, N.Y., huddled under an umbrella with her friend Suzanne Hassan, 17.

“We just kept on hanging on ’cause we love the Jonas Brothers so much. We’ll do anything for them,” Huang said, staking the No. 1 spot behind a barricade as she waited for the doors to open.

Though their sound is primarily guitar-fueled pop-rock, Nick Jonas says he’d like to write songs under an alias to switch things up – and see what happens.

“Maybe one day I’d write a song and somebody would sing it and then no one would really know that I wrote it,” he says.

“It would be kind of exciting, and I had heard that Prince did that, and it was just kind of a goal for me.”