Richards divorced Sheen after just four years of marriage in 2006, but the former couple apparently have become close friends in recent years.
During an appearance on Access Hollywood Live, the actress was quizzed on if she would ever consider dating Sheen again.
"I don't think so, I'm way too old for him… [Charlie] likes 20-year-olds," she joked.
Richards has shot a cameo appearance in Sheen's new sitcom Anger Management, which she described as a very fun experience.
"I'm so excited for the show and him and he asked if I would do an episode and I did… We actually have fun together," the actress joked.
She went on to say: "For us, we get along quite well. We see each other often… We met working, we worked together while we were married.
"I did a couple of episodes of Two and Half Men. This is the first thing we did after our divorce."
Charlie's father Martin Sheen will also make a guest appearance in Anger Management's first season.
Anger Management premieres on Thursday, June 28 at 9pm EST on FX.
Watch a preview of Anger Management below: