EXCLUSIVE

If you ever plan to get married, start taking notes -- because former "American Idol" champ Ruben Studdard just went through the CLEANEST divorce ever ... all thanks to his ironclad prenup.

TMZ broke the story ... Ruben filed for divorce in November from his wife Surata Zuri McCants, citing irreconcilable differences. The divorce was finalized in January.

It got hairy at first -- Zuri tried to get the judge in their divorce case to nullify the prenup, claiming Ruben blindsided her with the documents just days before the wedding, unfairly pressuring her into signing them.

But the judge wasn't buying it -- upholding the prenup, and awarding Zuri close to ZILCH in the divorce.

According to the final judgment, Ruben was not ordered to pay ANY spousal support or alimony ... and he gets to keep their home plus all his belongings -- jewelry, pensions, royalties, clothing, and all his cash. It was even ordered Zuri return the engagement ring.

Meanwhile, Zuri gets next to nothing -- her wedding dress, her photo albums, a 2006 BMW (which Ruben will pay off), a 10k property settlement, 2k for attorneys fees ... oh yeah, and her maiden name.