Liyang city, of East China's Jiangsu province, has been granted the title of "longevity town", becoming the 21st member of the group of towns known for producing long-living residents, Xinhua News Agency reported on Thursday.

Statistics show that although the total population is just 780,000, there were 57 centenarians living in the city as of March, 2011, and the average life span of Liyang city residents is 75.12 years, according to earlier reports by China News Service.

Only those towns and cities in which centenarians account for at least 0.007% of the total population for at least three consecutive years are qualified to apply for a title of "Longevity Town", according to Zhao Baohua, Vice-President of Gerontological Society of China.

Zhao said he believed the great ecological environment and healthy life styles are major contributors to Liyang people's longevity.

The environment surrounding the city may contribute to its long-living residents, with the forest coverage rate of the city at 28.15%, and selenium-rich soil in the southern part of the town. Farm produce grown in this area is thought to be good for local's health, as several studies have shown a possible link between cancer and selenium deficiency, according to China News Service.