Kim Kardashian did it BIG for her big 4-0 ... renting out a private island for a week of birthday celebrations.
The bday getaway was super lavish ... our sources say Kim flew 40 of her closest friends and family on a Boeing 777 to the private isle, where they were handed keys to their own private villas on the beach.
Kim's guest list included ... Kris, Khloe, Kourtney, Kendall, La La Anthony, Corey Gamble, NBA studs Devin Booker and Tristan Thompson, plus Scott and Mason Disick. We're told Kanye West was not present for Kim's actual birthday -- he had some work commitments -- but Yeezy joined the trip for the final few days.
Our sources say Kim picked out an island that hadn't seen any COVID cases ... and she asked all her guests to quarantine for 2 weeks before the trip and get multiple tests. Smart and safe.
In addition to private beachfront villas, we're told Kim hooked her guests up with Skims pajamas, KKW Beauty products, GoPro's, waterproof disposable cameras and lots of other island essentials. Now that's hospitality!
Our sources say Kim and co. spent the entire week dancing, whale watching, swimming in lagoons, kayaking, snorkeling, playing volleyball and enjoying outdoor dinners right on the sand. Like we said -- lavish.
We're told Kim even treated everyone to a private screening of "This is 40" on the beach.
Kim got a sweet surprise herself ... sources say she was treated to an hour-long birthday video tribute featuring her four kids, old childhood friends, family members, work associates and celeb pals like Cher, Jennifer Lopez, John Legend and Chrissy Teigen.