28191 has 4 divisors (see below), whose sum is σ = 37592. Its totient is φ = 18792.

The previous prime is 28183. The next prime is 28201. The reversal of 28191 is 19182.

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

It is not a de Polignac number, because 28191 - 2³ = 28183 is a prime.

It is a D-number.

It is a Duffinian number.

28191 is a lucky number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28111) 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, 4696 + ... + 4701.

It is an arithmetic number, because the mean of its divisors is an integer number (9398).

2²⁸¹⁹¹ is an apocalyptic number.

28191 is a deficient number, since it is larger than the sum of its proper divisors (9401).

28191 is an equidigital number, since it uses as much as digits as its factorization.

28191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9400.

The product of its digits is 144, while the sum is 21.

The square root of 28191 is about 167.9017569890. The cubic root of 28191 is about 30.4347795623.

Multiplying 28191 by its product of digits (144), we get a palindrome (4059504).

Subtracting from 28191 its reverse (19182), we obtain a palindrome (9009).

The spelling of 28191 in words is "twenty-eight thousand, one hundred ninety-one".