Provide the population of Arecibo in 2020.
population of Arecibo in 2020 refers to SUM(population_2020) where county = 'ARECIBO';
SELECT SUM(T2.population_2020) FROM country AS T1 INNER JOIN zip_data AS T2 ON T1.zip_code = T2.zip_code WHERE T1.county = 'ARECIBO'