28509817 has 16 divisors (see below), whose sum is σ = 34038400. Its totient is φ = 23856336.

The previous prime is 28509797. The next prime is 28509827. The reversal of 28509817 is 71890582.

It is not a de Polignac number, because 28509817 - 2¹⁵ = 28477049 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 28509817.

It is not an unprimeable number, because it can be changed into a prime (28509827) 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 15 ways as a sum of consecutive naturals, for example, 13783 + ... + 15715.

It is an arithmetic number, because the mean of its divisors is an integer number (2127400).

Almost surely, 2^28509817 is an apocalyptic number.

It is an amenable number.

28509817 is a deficient number, since it is larger than the sum of its proper divisors (5528583).

28509817 is an equidigital number, since it uses as much as digits as its factorization.

28509817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1997 (or 1983 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 40.

The square root of 28509817 is about 5339.4584931433. The cubic root of 28509817 is about 305.4908052231.

The spelling of 28509817 in words is "twenty-eight million, five hundred nine thousand, eight hundred seventeen".