20564522557 has 2 divisors, whose sum is σ = 20564522558. Its totient is φ = 20564522556.

The previous prime is 20564522519. The next prime is 20564522569. The reversal of 20564522557 is 75522546502.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12139852761 + 8424669796 = 110181^2 + 91786^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20564522557 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20564522357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10282261278 + 10282261279.

It is an arithmetic number, because the mean of its divisors is an integer number (10282261279).

Almost surely, 2^20564522557 is an apocalyptic number.

It is an amenable number.

20564522557 is a deficient number, since it is larger than the sum of its proper divisors (1).

20564522557 is an equidigital number, since it uses as much as digits as its factorization.

20564522557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 840000, while the sum is 43.

The spelling of 20564522557 in words is "twenty billion, five hundred sixty-four million, five hundred twenty-two thousand, five hundred fifty-seven".