20568809 has 4 divisors (see below), whose sum is σ = 20578116. Its totient is φ = 20559504.

The previous prime is 20568787. The next prime is 20568817. The reversal of 20568809 is 90886502.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 739600 + 19829209 = 860^2 + 4453^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20568809 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20568829) 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, 767 + ... + 6459.

It is an arithmetic number, because the mean of its divisors is an integer number (5144529).

Almost surely, 2^20568809 is an apocalyptic number.

It is an amenable number.

20568809 is a deficient number, since it is larger than the sum of its proper divisors (9307).

20568809 is an equidigital number, since it uses as much as digits as its factorization.

20568809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9306.

The product of its (nonzero) digits is 34560, while the sum is 38.

The square root of 20568809 is about 4535.2848863109. The cubic root of 20568809 is about 273.9910532181.

The spelling of 20568809 in words is "twenty million, five hundred sixty-eight thousand, eight hundred nine".