28756439 has 4 divisors (see below), whose sum is σ = 28838256. Its totient is φ = 28674624.

The previous prime is 28756391. The next prime is 28756447. The reversal of 28756439 is 93465782.

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 28756439 - 2⁸ = 28756183 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28756439.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28756939) 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, 40379 + ... + 41084.

It is an arithmetic number, because the mean of its divisors is an integer number (7209564).

Almost surely, 2^28756439 is an apocalyptic number.

28756439 is a deficient number, since it is larger than the sum of its proper divisors (81817).

28756439 is an equidigital number, since it uses as much as digits as its factorization.

28756439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81816.

The product of its digits is 362880, while the sum is 44.

The square root of 28756439 is about 5362.5030536122. The cubic root of 28756439 is about 306.3691523583.

Adding to 28756439 its reverse (93465782), we get a palindrome (122222221).

The spelling of 28756439 in words is "twenty-eight million, seven hundred fifty-six thousand, four hundred thirty-nine".