Katy Perry and Russell Brand Didn't Need Prenup

According to sources, Katy and Russell's marriage happened so fast, they never really had the opportunity to summon their lawyers and hash out a prenup ... nor did either really believe they needed one.

We're told both felt comfortable one wouldn't screw the other in the event of a divorce -- they both knew where the other person stood on money, life, religion ... everything.

TMZ broke the story ... Russell refused to accept $20 million of Katy's money he was entitled to as part of the divorce -- exactly half the money she made during the course of their marriage.

Sources tell us, Russell was never a materialistic person and never spent much -- he never got into entertainment for the money.

As one source put it, "Russell is a very simple person who doesn't need much to make him happy."

The source adds, "He would never take money that [Katy] earned. That's not Russell. And if it was the other way around, Katy wouldn't have taken it either. They respect each other too much."