28810809 has 14 divisors (see below), whose sum is σ = 43197546. Its totient is φ = 19206720.

The previous prime is 28810807. The next prime is 28810841. The reversal of 28810809 is 90801882.

It can be written as a sum of positive squares in only one way, i.e., 15327225 + 13483584 = 3915^2 + 3672^2 .

It is not a de Polignac number, because 28810809 - 2¹ = 28810807 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28810807) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 19032 + ... + 20489.

It is an arithmetic number, because the mean of its divisors is an integer number (3085539).

Almost surely, 2^28810809 is an apocalyptic number.

It is an amenable number.

28810809 is a deficient number, since it is larger than the sum of its proper divisors (14386737).

28810809 is an frugal number, since it uses more digits than its factorization.

28810809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39539 (or 39524 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 36.

The square root of 28810809 is about 5367.5701206412. The cubic root of 28810809 is about 306.5621155622.

The spelling of 28810809 in words is "twenty-eight million, eight hundred ten thousand, eight hundred nine".