But they're not making phone calls, they're spending most of that time on mobile apps.
At the top of the heap is Amazon, which packs lots of functionality into its mobile app. The Amazon app lets users shop, listen to e-books, and enjoy some capabilities of Alexa, the same virtual assistant that's in Amazon's Echo device.
Facebook has taken a different approach and created a variety of different apps. While Facebook doesn't have the number one spot, it counts four of its properties among the list of must-haves for millennials.
Mike Nudelman/Business Insider
This post originally appeared on Business Insider.