28108765 has 4 divisors (see below), whose sum is σ = 33730524. Its totient is φ = 22487008.

The previous prime is 28108673. The next prime is 28108777. The reversal of 28108765 is 56780182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56780182 = 2 ⋅28390091.

It can be written as a sum of positive squares in 2 ways, for example, as 4401604 + 23707161 = 2098^2 + 4869^2 .

It is a cyclic number.

It is not a de Polignac number, because 28108765 - 2¹³ = 28100573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2810872 + ... + 2810881.

It is an arithmetic number, because the mean of its divisors is an integer number (8432631).

Almost surely, 2^28108765 is an apocalyptic number.

It is an amenable number.

28108765 is a deficient number, since it is larger than the sum of its proper divisors (5621759).

28108765 is an equidigital number, since it uses as much as digits as its factorization.

28108765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5621758.

The product of its (nonzero) digits is 26880, while the sum is 37.

The square root of 28108765 is about 5301.7699874664. The cubic root of 28108765 is about 304.0515732273.

The spelling of 28108765 in words is "twenty-eight million, one hundred eight thousand, seven hundred sixty-five".