After WhatsApp announced a more Facebook-friendly privacy policy, tech billionaire Elon Musk nonchalantly suggested using a more secure, encrypted messaging service. As Apple App Store and Google Play rankings show, people followed Musk's advice.

Musk's tweet came in early last Thursday with only two words: "Use Signal." That ignited a download storm for the WhatsApp alternative. As longtime users noticed, more and more notifications were popping up about new users joining the messaging app. With so many new downloads, there was even a wait.

Data from app analytics firm Apptopia shows that on Thursday alone, after the tweet, there were 63,345 Signal app downloads around the world. The day before, there were 45,086 downloads. That's on both iOS and Android devices.

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But it took a full day for Musk's suggestion to really hit. The day after the Elon tweet, Signal hit a record number of downloads: about 90,000. Before that, the highest download day for Signal was June 1, amid Black Lives Matter protests.

SEE ALSO:What is Signal? The basics of the most secure messaging app.

Over the weekend, Signal hit the number one app in all of the App Store for iOS devices. It's still at the top slot as of Monday afternoon. It's never been at the top before. For Android users, it ranked number seven overall, also the highest it's ever been for the Google Play store.