20569209 has 4 divisors (see below), whose sum is σ = 27425616. Its totient is φ = 13712804.

The previous prime is 20569193. The next prime is 20569217. The reversal of 20569209 is 90296502.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20569209 - 2⁴ = 20569193 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20569209.

It is not an unprimeable number, because it can be changed into a prime (20569259) 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, 3428199 + ... + 3428204.

It is an arithmetic number, because the mean of its divisors is an integer number (6856404).

Almost surely, 2^20569209 is an apocalyptic number.

It is an amenable number.

20569209 is a deficient number, since it is larger than the sum of its proper divisors (6856407).

20569209 is an equidigital number, since it uses as much as digits as its factorization.

20569209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6856406.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 20569209 is about 4535.3289847595. The cubic root of 20569209 is about 273.9928293007.

The spelling of 20569209 in words is "twenty million, five hundred sixty-nine thousand, two hundred nine".