28491 has 4 divisors (see below), whose sum is σ = 37992. Its totient is φ = 18992.

The previous prime is 28477. The next prime is 28493. The reversal of 28491 is 19482.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28491 - 2¹⁴ = 12107 is a prime.

It is a D-number.

It is a nialpdrome in base 14.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 28491.

It is not an unprimeable number, because it can be changed into a prime (28493) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4746 + ... + 4751.

It is an arithmetic number, because the mean of its divisors is an integer number (9498).

2²⁸⁴⁹¹ is an apocalyptic number.

28491 is a deficient number, since it is larger than the sum of its proper divisors (9501).

28491 is an equidigital number, since it uses as much as digits as its factorization.

28491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9500.

The product of its digits is 576, while the sum is 24.

The square root of 28491 is about 168.7927723571. The cubic root of 28491 is about 30.5423580594.

Subtracting from 28491 its reverse (19482), we obtain a palindrome (9009).

It can be divided in two parts, 2849 and 1, that added together give a triangular number (2850 = T₇₅).

The spelling of 28491 in words is "twenty-eight thousand, four hundred ninety-one".