28565809 has 2 divisors, whose sum is σ = 28565810. Its totient is φ = 28565808.

The previous prime is 28565791. The next prime is 28565827. The reversal of 28565809 is 90856582.

It is a balanced prime because it is at equal distance from previous prime (28565791) and next prime (28565827).

It can be written as a sum of positive squares in only one way, i.e., 24453025 + 4112784 = 4945^2 + 2028^2 .

It is a cyclic number.

It is not a de Polignac number, because 28565809 - 2⁵ = 28565777 is a prime.

It is not a weakly prime, because it can be changed into another prime (28565869) 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 as a sum of consecutive naturals, namely, 14282904 + 14282905.

It is an arithmetic number, because the mean of its divisors is an integer number (14282905).

Almost surely, 2^28565809 is an apocalyptic number.

It is an amenable number.

28565809 is a deficient number, since it is larger than the sum of its proper divisors (1).

28565809 is an equidigital number, since it uses as much as digits as its factorization.

28565809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 172800, while the sum is 43.

The square root of 28565809 is about 5344.6991496248. The cubic root of 28565809 is about 305.6906645151.

The spelling of 28565809 in words is "twenty-eight million, five hundred sixty-five thousand, eight hundred nine".