20522561957 has 4 divisors (see below), whose sum is σ = 20522854380. Its totient is φ = 20522269536.

The previous prime is 20522561929. The next prime is 20522561977. The reversal of 20522561957 is 75916522502.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 75916522502 = 2 ⋅37958261251.

It can be written as a sum of positive squares in 2 ways, for example, as 19915136641 + 607425316 = 141121^2 + 24646^2 .

It is a cyclic number.

It is not a de Polignac number, because 20522561957 - 2²⁰ = 20521513381 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20522561977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29243 + ... + 204695.

It is an arithmetic number, because the mean of its divisors is an integer number (5130713595).

It is a Poulet number, since it divides 2^20522561956-1.

Almost surely, 2^20522561957 is an apocalyptic number.

20522561957 is the 116969-th pentagonal number.

It is an amenable number.

20522561957 is a deficient number, since it is larger than the sum of its proper divisors (292423).

20522561957 is a wasteful number, since it uses less digits than its factorization.

20522561957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 292422.

The product of its (nonzero) digits is 378000, while the sum is 44.

The spelling of 20522561957 in words is "twenty billion, five hundred twenty-two million, five hundred sixty-one thousand, nine hundred fifty-seven".