20561632057 has 2 divisors, whose sum is σ = 20561632058. Its totient is φ = 20561632056.

The previous prime is 20561632031. The next prime is 20561632067. The reversal of 20561632057 is 75023616502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18360521001 + 2201111056 = 135501^2 + 46916^2 .

It is a cyclic number.

It is not a de Polignac number, because 20561632057 - 2¹⁹ = 20561107769 is a prime.

It is not a weakly prime, because it can be changed into another prime (20561632067) 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 as a sum of consecutive naturals, namely, 10280816028 + 10280816029.

It is an arithmetic number, because the mean of its divisors is an integer number (10280816029).

Almost surely, 2^20561632057 is an apocalyptic number.

It is an amenable number.

20561632057 is a deficient number, since it is larger than the sum of its proper divisors (1).

20561632057 is an equidigital number, since it uses as much as digits as its factorization.

20561632057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 75600, while the sum is 37.

The spelling of 20561632057 in words is "twenty billion, five hundred sixty-one million, six hundred thirty-two thousand, fifty-seven".