Medford-based Century Bancorp Inc. earned $13.6 million in 2010, a 33.6 percent increase compared to the $10.2 million earned in 2009.

Century Bancorp also declared a regular quarterly dividend of 12-cents per share on the company’s Class A common stock and 6-cents per share on the company’s Class B common stock, according to a statement. The dividends will be payable Feb. 15 to stockholders of record on Feb. 1.