91321808819 has 4 divisors (see below), whose sum is σ = 96693679944. Its totient is φ = 85949937696.

The previous prime is 91321808807. The next prime is 91321808849. The reversal of 91321808819 is 91880812319.

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

It is not a de Polignac number, because 91321808819 - 2²⁸ = 91053373363 is a prime.

It is a super-2 number, since 2×91321808819² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91321808849) 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, 2685935537 + ... + 2685935570.

It is an arithmetic number, because the mean of its divisors is an integer number (24173419986).

Almost surely, 2^91321808819 is an apocalyptic number.

91321808819 is a deficient number, since it is larger than the sum of its proper divisors (5371871125).

91321808819 is a wasteful number, since it uses less digits than its factorization.

91321808819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5371871124.

The product of its (nonzero) digits is 248832, while the sum is 50.

The spelling of 91321808819 in words is "ninety-one billion, three hundred twenty-one million, eight hundred eight thousand, eight hundred nineteen".