20565566565 has 16 divisors (see below), whose sum is σ = 33164003328. Its totient is φ = 10881936576.

The previous prime is 20565566531. The next prime is 20565566569. The reversal of 20565566565 is 56566556502.

It is not a de Polignac number, because 20565566565 - 2²³ = 20557177957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20565566569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5395882 + ... + 5399691.

It is an arithmetic number, because the mean of its divisors is an integer number (2072750208).

Almost surely, 2^20565566565 is an apocalyptic number.

It is an amenable number.

20565566565 is a deficient number, since it is larger than the sum of its proper divisors (12598436763).

20565566565 is a wasteful number, since it uses less digits than its factorization.

20565566565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10795708.

The product of its (nonzero) digits is 8100000, while the sum is 51.

The spelling of 20565566565 in words is "twenty billion, five hundred sixty-five million, five hundred sixty-six thousand, five hundred sixty-five".