8991

8991 is a natural number that follows 8990 and precedes 8992. In decimal notation it is written as 8991. In mathematics, 8991 is a composite number with prime factorization 3^5 × 37, which gives it twelve positive divisors: 1, 3, 9, 27, 81, 243, 37, 111, 333, 999, 2997, and 8991.

The sum of the digits of 8991 is 27, so the number is divisible by 9; indeed 8991 divided by 9 equals 999. It is also divisible by 27 (8991 = 27 × 333) and by 81 (8991 = 81 × 111). Consequently, 8991 is a Harshad (Niven) number in base 10, because it is divisible by the sum of its digits. Its digital root is 9.

In base representations, 8991 is written as 10001100011111 in binary and as 0x231F in hexadecimal. The factorization 3^5 × 37 shows that 8991 is the product of a power of 3 and a prime number, which constrains its divisors and parity properties.

There is no widely notable mathematical constant or famous theorem specifically associated with the number 8991. It is primarily of interest as an example of a composite number with a straightforward prime factorization, and as a case for base conversion and divisor counting in introductory number theory.