The number "391" is an integer that follows 390 and precedes 392. It is an odd number and can be expressed as the sum of two prime numbers: 389 and 2. In Roman numerals, 391 is represented as CCCXCI. In mathematics, 391 is classified as a composite number, meaning it has divisors other than 1 and itself. Its prime factorization is 17 × 23, indicating that it can be divided evenly by these two prime numbers. The number also appears in various contexts, such as in area codes or postal codes.