20445665 has 4 divisors (see below), whose sum is σ = 24534804. Its totient is φ = 16356528.

The previous prime is 20445637. The next prime is 20445697. The reversal of 20445665 is 56654402.

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 13512976 + 6932689 = 3676^2 + 2633^2 .

It is a cyclic number.

It is not a de Polignac number, because 20445665 - 2²⁰ = 19397089 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2044562 + ... + 2044571.

It is an arithmetic number, because the mean of its divisors is an integer number (6133701).

Almost surely, 2^20445665 is an apocalyptic number.

It is an amenable number.

20445665 is a deficient number, since it is larger than the sum of its proper divisors (4089139).

20445665 is an equidigital number, since it uses as much as digits as its factorization.

20445665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4089138.

The product of its (nonzero) digits is 28800, while the sum is 32.

The square root of 20445665 is about 4521.6882908931. The cubic root of 20445665 is about 273.4431700484.

The spelling of 20445665 in words is "twenty million, four hundred forty-five thousand, six hundred sixty-five".