Katy Perry After Russell Brand Divorce:

Katy Perry's life is completely different compared to just two years ago. While promoting her upcoming third studio album Prism, the 28-year-old pop star gave a sneak peek into her life with boyfriend John Mayer -- and why he's such a smarty pants, shedding some light on just how her life has changed since her divorce from comedianRussell Brand.

"He literally is a genius, as is evident from his songwriting," the "Roar" singer told Billboard in its latest issue about Mayer. "I always tell him, 'Darling, you know I'm going to have to give your mind to science after you've passed, because we're going to have to understand how all these sparks work.'"

One of the reasons Perry finds the 35-year-old "Say" singer so smart? He's a puzzle master! "We'll be in bed, and he'll be doing the crossword puzzle. Every night, he tries to finish it in under 10 minutes. When he puts his mind to something, he really gets it done very well. I always ask for his help."

The "Firework" star is focused on her new album -- set to hit stores Oct. 22 -- and is on a different path from just two years ago. In the Billboard interview, Perry also dishes on when veteran journalist Barbara Walters threw "shade" at her during Walters' Most Fascinating People of 2011 special. At the time, Perry knew her 14-month marriage to husband Brand was close to being over, and now admits she wish she never sat down for the chat. 

"I shouldn't have done the interview: I was playing Madison Square Garden that same night, and I knew that the end of my marriage was coming," she recalled. "I'd prepped everyone that I was running late, but Barbara showed up at the original time anyway. When I got there, I apologized immediately, but then she said to me, 'You know, I've only ever waited for one other person this long, and you know who that person was? Judy Garland. You know how she turned out, right?'"

Perry added: "I was like, 'Oh, snap! Yes, bitch!' I think it's the coolest thing that Barbara Waltersshaded me. I just couldn't tell her as we were sitting down for a mega-interview, 'Hey, my marriage is falling apart. Give me a break.'"

Brand, 38, would later file for divorce on Dec. 30, 2011, just two weeks after the special aired. The difficult situation Perry experienced at the time would soon lead to fighting off suicidal thoughts, which she then wrote about in her upcoming "By the Grace of God" track. "That song is evident of how tough it really was at a certain point. I asked myself, 'Do I want to endure? Should I continue living?'" she said. "All the songs are real-life moments. I can only write autobiographically. I put all the evidence in the music. I tell my fans if they want to know the real truth about stuff, just listen to the songs."