https://www.usatoday.com/story/news/politics/elections/2016/06/01/donald-trump-lawsuits-legal-battles/84995854/

They identified 3,500 cases, 1,900 where he was plaintiff, 1,450 where he was the defendant, and 150 which were legal matters rather than lawsuits, such bankruptcy filings.

The article has an exhibit where they break out the various actions by source/subject. (If you use your browser's find-in-page function, usually ctrl-F, search for: Trump lawsuits by the numbers )

1,700 of the cases related to the casinos, while 700 were personal injury suits aka slip-n-falls on his various properties. (There are more details in the article.) There's also some information on what happened to the cases, although that's not complete.

After one of his attorneys told them that his number of suits was lower than most comparable organizations, they checked on the legal activities of 5 other major real estate developers. He had more suits where he was either the plaintiff or defendant than the other 5 developers combined.