91638612823 has 4 divisors (see below), whose sum is σ = 91641210408. Its totient is φ = 91636015240.

The previous prime is 91638612733. The next prime is 91638612827. The reversal of 91638612823 is 32821683619.

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 91638612823 - 2⁹ = 91638612311 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91638612827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1245136 + ... + 1316677.

It is an arithmetic number, because the mean of its divisors is an integer number (22910302602).

Almost surely, 2^91638612823 is an apocalyptic number.

91638612823 is a deficient number, since it is larger than the sum of its proper divisors (2597585).

91638612823 is a wasteful number, since it uses less digits than its factorization.

91638612823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2597584.

The product of its digits is 746496, while the sum is 49.

The spelling of 91638612823 in words is "ninety-one billion, six hundred thirty-eight million, six hundred twelve thousand, eight hundred twenty-three".