Robbie Williams -- I'm Interested in Michael Jackson's Death House

The first prospective buyer who came to look at the house where Michael Jackson died was singer Robbie Williams ... and who knew he was so loaded?

Our spies saw Robbie roll up to the house Thursday afternoon in his Range Rover.

The house was just listed -- again -- this time the asking price is $23.9 million.

We know anyone who looks at the estate has to pre-qualify ... meaning they have to show they can afford the steep purchase price.

As for Robbie, a London newspaper estimates his 2011 net worth at $149 mil. Robbie currently owns a home in the Beverly Hills area -- he paid $16 mil back in 2008. And he bought a house down the street and uses the land as a soccer field. Now that's rich.

As for the Holmby Hills estate -- Michael was renting it from Hubert Guez, the CFO of Ed Hardy. The house is 17,000 square feet, with 7 bedrooms and 13 bathrooms.

As for whether Robbie is interested in making an offer ... his rep had no comment.