91564160561 has 4 divisors (see below), whose sum is σ = 91564966500. Its totient is φ = 91563354624.

The previous prime is 91564160551. The next prime is 91564160573. The reversal of 91564160561 is 16506146519.

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.

It can be written as a sum of positive squares in 2 ways, for example, as 43579067536 + 47985093025 = 208756^2 + 219055^2 .

It is a cyclic number.

It is not a de Polignac number, because 91564160561 - 2³⁰ = 90490418737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91564160551) 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 3 ways as a sum of consecutive naturals, for example, 197696 + ... + 471393.

It is an arithmetic number, because the mean of its divisors is an integer number (22891241625).

Almost surely, 2^91564160561 is an apocalyptic number.

It is an amenable number.

91564160561 is a deficient number, since it is larger than the sum of its proper divisors (805939).

91564160561 is a wasteful number, since it uses less digits than its factorization.

91564160561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 805938.

The product of its (nonzero) digits is 194400, while the sum is 44.

The spelling of 91564160561 in words is "ninety-one billion, five hundred sixty-four million, one hundred sixty thousand, five hundred sixty-one".