Katy Perry's $25 million deal to be the lead judge on "American Idol" wasn't just for her -- she says she struck a blow for women everywhere who've been underpaid to do the same job as a man.

Katy was on NYC'S WKTU radio Tuesday and told "Cubby and Carolina Bermudez In the Morning" ... she's proud as hell her fat paycheck is more than "pretty much" any man made before her.

The pop star goes on to give a preview of what kind of judge she's going to be, and said she's the perfect fit for the show at the perfect time.

As we reported ... Perry's getting paid more than most of her big name 'Idol' predecessors. However, she'll need a massive raise before she matches Simon Cowell's reported $45 mil a year.