Signal is the world’s most widely used truly private messaging app, and our cryptographic technologies provide extra layers of privacy beyond the Signal app itself. Since launching in 2013, the Signal Protocol—our end-to-end encryption technology—has become the de facto standard for private commu...
I mean, without browsing levels.fyi or anything like that you can get 4 to 10 software engineers for 1 million (anything from 100k to 250k depending on location, experience, etc.).
Not all employees are engineers but that would imply 80 to 200 staff for the 20 million they state.
That’s only the component paid to the actual staff though. There are additional costs like Healthcare, unemployment, social security, etc, and other benefits that may not be included in wages (though some portion may be deducted from salaries), but they are including in that statement / summary.
For an app like signal you would/should be at the top of that range. You want to acquire and maintain talent. Not every dev has the chops.
It says that they have 50 full time employees.