Is hangouts installed by default (i don't know), seem to have a billion installs, which looked a bit too high for both default-install, and non-default install.
It's installed by default on most Android devices, and a large portion of Asia's handset market (India) is dominated by Android, but messaging in India is dominated by Whatsapp. So almost-a-billion is bloated download numbers of Indian smartphones coming with hangouts installed, but none of them using it.
