91991338658 has 4 divisors (see below), whose sum is σ = 137987007990. Its totient is φ = 45995669328.

The previous prime is 91991338603. The next prime is 91991338661. The reversal of 91991338658 is 85683319919.

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

It can be written as a sum of positive squares in only one way, i.e., 84098260009 + 7893078649 = 289997^2 + 88843^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 91991338658.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 22997834663 + ... + 22997834666.

Almost surely, 2^91991338658 is an apocalyptic number.

91991338658 is a deficient number, since it is larger than the sum of its proper divisors (45995669332).

91991338658 is a wasteful number, since it uses less digits than its factorization.

91991338658 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45995669331.

The product of its digits is 12597120, while the sum is 62.

The spelling of 91991338658 in words is "ninety-one billion, nine hundred ninety-one million, three hundred thirty-eight thousand, six hundred fifty-eight".