[nh2]

Google alone had 2.5 million servers in 2016 as per estimate [1], and 0.9 million in 2011 in [2].

So a reasonable guess for today seems > 5 million.

[1] https://en.wikipedia.org/wiki/Google_data_centers

[2] https://www.datacenterknowledge.com/archives/2011/08/01/repo...

[pjmlp]

I am missing the numbers for the rest of the world.