Janet Jackson is worth an estimated $150 million -- but she just got engaged to a dude who looked at her bank account, laughed and said, "Awww. Isn't that cute?"

Janet's brothed is 37-year-old billionaire businessman Wissam Al Mana, who -- with his two brothers -- runs the Al Mana Luxury Company. It has a retail fashion portfolio including Hermes, Sonia Rykiel and Agent Provocateur, and it's a shareholder in the Saks Fifth Avenue stores in Dubai, Doha, Bahrain and Kuwait. His family's businesses also include a slew of different companies in the Gulf region.

Wissam reportedly popped the question to Jackson a few months ago and gave her an engagement ring so huge and so expensive that she keeps it "locked up" for fear she'll lose it.

The couple are planning to tie the knot next spring in Al Mana's homeland of Qatar in a wedding that "will cost millions," partly because he's “flying in all of Janet's friends and family on private jets." Hope he has lots of pilots on the payroll, because Jackson has seven siblings and 20 nieces and nephews alone.

He also wants to get a "top chef to create a custom menu," a source said, with another comparing the upcoming wedding to a “circus.” (Too bad Michael will miss it -- he'd have enjoyed that.)

Jackson is supposedly happy to be settling down again after her 2009 split with Jermaine Dupri, with an insider saying the 46-year-old star "wants kids ... if she can't have them, she will adopt."

And if she can't birth or adopt them, she's about to be rich enough that she could probably just start buying them from random strangers off the street.

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