181K - If all AdSense publishers joined in, we could create 181,000 football teams.
I'm assuming Assocation Football (soccer) since it's the World Cup:
181,000 x 11 = 1,991,000
However 12 substitutes are allowed per team:
181,000 x 12 = 2,172,000
I've seen the 2 million mentioned several times so do we take that as a given nowadays?