28510891 has 4 divisors (see below), whose sum is σ = 28549312. Its totient is φ = 28472472.

The previous prime is 28510877. The next prime is 28510927. The reversal of 28510891 is 19801582.

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 28510891 - 2¹³ = 28502699 is a prime.

It is a super-2 number, since 2×28510891² = 1625741811227762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28510861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18075 + ... + 19588.

It is an arithmetic number, because the mean of its divisors is an integer number (7137328).

Almost surely, 2^28510891 is an apocalyptic number.

28510891 is a deficient number, since it is larger than the sum of its proper divisors (38421).

28510891 is an equidigital number, since it uses as much as digits as its factorization.

28510891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38420.

The product of its (nonzero) digits is 5760, while the sum is 34.

The square root of 28510891 is about 5339.5590641925. The cubic root of 28510891 is about 305.4946412468.

The spelling of 28510891 in words is "twenty-eight million, five hundred ten thousand, eight hundred ninety-one".