20444640665 has 4 divisors (see below), whose sum is σ = 24533568804. Its totient is φ = 16355712528.

The previous prime is 20444640641. The next prime is 20444640673. The reversal of 20444640665 is 56604644402.

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 13983535504 + 6461105161 = 118252^2 + 80381^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20444640665 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, 2044464062 + ... + 2044464071.

It is an arithmetic number, because the mean of its divisors is an integer number (6133392201).

Almost surely, 2^20444640665 is an apocalyptic number.

It is an amenable number.

20444640665 is a deficient number, since it is larger than the sum of its proper divisors (4088928139).

20444640665 is an equidigital number, since it uses as much as digits as its factorization.

20444640665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4088928138.

The product of its (nonzero) digits is 552960, while the sum is 41.

The spelling of 20444640665 in words is "twenty billion, four hundred forty-four million, six hundred forty thousand, six hundred sixty-five".