The number "91" is an integer that follows 90 and precedes 92. It is an odd number and can be expressed as the sum of two prime numbers: 43 and 48. In mathematics, it is also known as a composite number because it has divisors other than 1 and itself. In the context of geography, 91 is the country code for India in the international dialing system. This means that when making a phone call to India from another country, you would start with the number 91 before dialing the local number.