The immense number of C bugs is not merely due to C's popularity. Other languages lead to less buggy and more secure code.

This is largely due to memory safety. However, immutability is also known to reduce bugs and be more secure (as many security related bugs are due to mutability). Lastly, superior concurrency constructs also have this bug-reducing effect.

That said I haven't looked into empirical studies. But I feel like it is just factually the case, at least for memory safety, that in most other languages you literally are unable to create entire classes of bugs that are possible in C. So just logically thinking about it, I don't even see why you'd need to see empirical studies. It should be quite obvious!

Although it'd be cool to see the empirical research too! Maybe someone else can reply with links to studies.