The number "646" is an integer that follows 645 and precedes 647. It is an even number, meaning it is divisible by 2 without a remainder. In mathematics, 646 can be factored into its prime components, which are 2 and 323. In the context of area codes, 646 is a telephone area code in the North American Numbering Plan. It serves parts of New York City, particularly the boroughs of Manhattan and parts of the Bronx. This area code was established in 1999 to accommodate the growing demand for phone numbers in these densely populated areas.