Shanghai covers an area of 6,340 square kilometers and Longnan covers an area of 27,838 square kilometers. Because 1 km2 is equal to 1 km2, and 6340 km2 is equal to 6340 km2, which is relatively large in Shanghai. Shanghai (referred to as "Shanghai and Shenzhen" for short) is a national central city of China, a megacity, a core city of Shanghai, Hangzhou and Ningbo, an international economic, financial, trade, shipping and scientific and technological innovation center, and the first batch of coastal open cities. Located at the mouth of the Yangtze River, Shanghai is the leading city in the Yangtze River Economic Belt, facing Kyushu Island across the sea, Hangzhou Bay in the south and Jiangsu and Zhejiang provinces in the northwest.