How many megacities does China have? The United Nations puts it at six. Try 15.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/china-has-even-more-megacities-you-thought
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/bloomberg
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/habitat-and-urbanisation
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/china
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/urbanisation
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/air-pollution
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/development