20809272665 has 4 divisors (see below), whose sum is σ = 24971127204. Its totient is φ = 16647418128.

The previous prime is 20809272647. The next prime is 20809272677. The reversal of 20809272665 is 56627290802.

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 3592683721 + 17216588944 = 59939^2 + 131212^2 .

It is a cyclic number.

It is not a de Polignac number, because 20809272665 - 2¹² = 20809268569 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, 2080927262 + ... + 2080927271.

It is an arithmetic number, because the mean of its divisors is an integer number (6242781801).

Almost surely, 2^20809272665 is an apocalyptic number.

It is an amenable number.

20809272665 is a deficient number, since it is larger than the sum of its proper divisors (4161854539).

20809272665 is an equidigital number, since it uses as much as digits as its factorization.

20809272665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4161854538.

The product of its (nonzero) digits is 725760, while the sum is 47.

The spelling of 20809272665 in words is "twenty billion, eight hundred nine million, two hundred seventy-two thousand, six hundred sixty-five".