The estimated Scrutiny number of participants Participation ranges Cause_to_be_included widely , from 600,000 people quoted Statement by some media , statisticians such as Llorenç Badiella from the Autonomous University of Barcelona or the delegation of the Spanish government in Catalonia to 1.5 million according to Catalan public sources such as Barcelona 's Municipal Police or Catalonia 's Department of the Interior , with a maximum estimate of about 2 million according to the organizers .