20565122009 has 2 divisors, whose sum is σ = 20565122010. Its totient is φ = 20565122008.

The previous prime is 20565121931. The next prime is 20565122021. The reversal of 20565122009 is 90022156502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19913443225 + 651678784 = 141115^2 + 25528^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20565122009 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (20565122029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10282561004 + 10282561005.

It is an arithmetic number, because the mean of its divisors is an integer number (10282561005).

Almost surely, 2^20565122009 is an apocalyptic number.

It is an amenable number.

20565122009 is a deficient number, since it is larger than the sum of its proper divisors (1).

20565122009 is an equidigital number, since it uses as much as digits as its factorization.

20565122009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10800, while the sum is 32.

The spelling of 20565122009 in words is "twenty billion, five hundred sixty-five million, one hundred twenty-two thousand, nine".