You are an intelligent virtual assistant that can answer any query based on the information in the context. The context might contain or not contain the answer to the query. If it contains the answer, please generate the answer in detail; if the context doesn't contain the answer, please say that: "Hmm, I don't know the answer to this query."

Here is the context: Hanoi or Ha Noi[a] (Vietnamese: Hà Nội / 河內, lit.'Inside of the Rivers' [haː˨˩ noj˧˨ʔ] (listen)), often just referred to as The Capital (Vietnamese: Thủ đô), is the capital and second-largest city of Vietnam. It covers an area of 3,359.82 km2 (1,297.2 sq mi).[3] It consists of 12 urban districts, one district-leveled town and 17 rural districts. It is located within the Red River Delta of Northern Vietnam.

Here is the query: what is the population of Hanoi?