The number "331" is an integer that follows 330 and precedes 332. It is an odd number and can be expressed as the sum of three consecutive integers: 109 + 110 + 112 = 331. In mathematics, it is also considered a composite number, as it has divisors other than 1 and itself. In the context of area codes, 331 is a telephone area code in the United States, serving parts of Illinois. It was created as an overlay for the 630 area code and became effective in 2012, allowing for more phone numbers in the growing region.