28811 has 4 divisors (see below), whose sum is σ = 29472.
Its totient is φ = 28152.
The previous prime is 28807. The next prime is 28813. The reversal of 28811 is 11882.
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 28811 - 22 = 28807 is a prime.
It is a Duffinian number.
It is a plaindrome in base 7.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 28811.
It is not an unprimeable number, because it can be changed into a prime (28813) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 260 + ... + 353.
It is an arithmetic number, because the mean of its divisors is an integer number (7368).
228811 is an apocalyptic number.
28811 is a deficient number, since it is larger than the sum of its proper divisors (661).
28811 is an equidigital number, since it uses as much as digits as its factorization.
28811 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 660.
The product of its digits is 128, while the sum is 20.
The square root of 28811 is about 169.7380334516.
The cubic root of 28811 is about 30.6562793007.
It can be divided in two parts, 2881 and 1, that added together give a palindrome (2882).
The spelling of 28811 in words is "twenty-eight thousand, eight hundred eleven".