91665056639 has 4 divisors (see below), whose sum is σ = 98716214856. Its totient is φ = 84613898424.

The previous prime is 91665056617. The next prime is 91665056647. The reversal of 91665056639 is 93665056619.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 91665056639 - 2⁸ = 91665056383 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 (91665056699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3525579089 + ... + 3525579114.

It is an arithmetic number, because the mean of its divisors is an integer number (24679053714).

Almost surely, 2^91665056639 is an apocalyptic number.

91665056639 is a deficient number, since it is larger than the sum of its proper divisors (7051158217).

91665056639 is a wasteful number, since it uses less digits than its factorization.

91665056639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7051158216.

The product of its (nonzero) digits is 7873200, while the sum is 56.

The spelling of 91665056639 in words is "ninety-one billion, six hundred sixty-five million, fifty-six thousand, six hundred thirty-nine".