The number 640 is an integer that follows 639 and precedes 641. It is an even number, meaning it is divisible by 2 without a remainder. In mathematics, 640 can be expressed as the product of its prime factors: 2^7 \times 5. In terms of measurement, 640 can refer to various units, such as 640 acres, which is equivalent to one square mile. This measurement is often used in land area calculations in the United States, particularly in agriculture and real estate. Additionally, 640 is a common resolution in digital images, specifically 640x480 pixels, known as VGA resolution.