20855609 has 4 divisors (see below), whose sum is σ = 20908020. Its totient is φ = 20803200.

The previous prime is 20855603. The next prime is 20855621. The reversal of 20855609 is 90655802.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20748025 + 107584 = 4555^2 + 328^2 .

It is a cyclic number.

It is not a de Polignac number, because 20855609 - 2¹² = 20851513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20855603) 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, 25604 + ... + 26405.

It is an arithmetic number, because the mean of its divisors is an integer number (5227005).

Almost surely, 2^20855609 is an apocalyptic number.

It is an amenable number.

20855609 is a deficient number, since it is larger than the sum of its proper divisors (52411).

20855609 is an equidigital number, since it uses as much as digits as its factorization.

20855609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52410.

The product of its (nonzero) digits is 21600, while the sum is 35.

The square root of 20855609 is about 4566.7941709694. The cubic root of 20855609 is about 275.2586393164.

The spelling of 20855609 in words is "twenty million, eight hundred fifty-five thousand, six hundred nine".