28000809 has 10 divisors (see below), whose sum is σ = 41828490. Its totient is φ = 18667152.

The previous prime is 28000799. The next prime is 28000831. The reversal of 28000809 is 90800082.

It can be written as a sum of positive squares in only one way, i.e., 21650409 + 6350400 = 4653^2 + 2520^2 .

It is not a de Polignac number, because 28000809 - 2¹⁶ = 27935273 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (28000849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 172764 + ... + 172925.

It is an arithmetic number, because the mean of its divisors is an integer number (4182849).

Almost surely, 2^28000809 is an apocalyptic number.

It is an amenable number.

28000809 is a deficient number, since it is larger than the sum of its proper divisors (13827681).

28000809 is an equidigital number, since it uses as much as digits as its factorization.

28000809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 345701 (or 345692 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 28000809 is about 5291.5790648917. The cubic root of 28000809 is about 303.6618216838.

The spelling of 28000809 in words is "twenty-eight million, eight hundred nine", and thus it is an aban number.