R. Kelly is some kind of mad, bulletproof genius, impervious to scandal and capable of almost anything on record and on stage.

After taking his already wildly successful career to stratospheric heights with “I Believe I Can Fly,” a gospel-based inspirational song, he spent the next few years dodging repeated allegations that he had sex with underage girls.

He still faces 14 charges, all stemming from a videotape that allegedly shows Kelly and a 14-year-old.

But what should have been career suicide has instead turned into a long string of No. 1 albums, most filled with songs about sex, and the insanely inspired “Trapped in the Closet,” a video “hip-hopera” that’s pure lunacy.

How does he do it?

Dude works hard, for one thing. Saturday night at Freedom Hall, Kelly put on an entertaining, even charming, show for around 10,000 faithful fans. From the moment he climbed onto a stage tricked out as a boxing ring, wearing a robe emblazoned with “Champ” across the back, Kelly rarely slowed down.

He also rarely focused. This was ADHD r&b, with Kelly usually singing no more than 30 to 45 seconds of any one song. Sometimes he didn’t even get to the chorus before moving on, and the show was 15 minutes deep before he made it past 90 seconds (on “Double Up,” appropriately enough).

He promised to sing all of his hits, and he might actually have sung at least a verse of each.

Kelly pulled it off by keeping the pace frenetic and the energy high while throwing a few wild punches that didn’t quite connect. At one point, he returned after a costume change in 1920s-style clothes while his pianist played ragtime, then “conducted” a minute or two of Beethoven before segueing into a disco production of “Step In the Name of Love.”

It was bizarre, but then again, this is a guy who’s written a hip-hopera about a cheating wife, gay pastor, trigger-happy thug, trailer-trash girl and a gifted midget. So maybe it was actually kind of normal.

Keyshia Cole and J. Holiday opened with brief sets. Holiday’s bedroom r&b still needs some maturing, but Cole delivered a nice set that had elements of classic r&b dating back to the 1970s sprinkled throughout.