991558855199 has 4 divisors (see below), whose sum is σ = 1081700569320. Its totient is φ = 901417141080.

The previous prime is 991558855187. The next prime is 991558855247.

991558855199 is nontrivially palindromic in base 10.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991558855199 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 (991558855499) 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, 45070857044 + ... + 45070857065.

It is an arithmetic number, because the mean of its divisors is an integer number (270425142330).

Almost surely, 2^991558855199 is an apocalyptic number.

991558855199 is a deficient number, since it is larger than the sum of its proper divisors (90141714121).

991558855199 is a wasteful number, since it uses less digits than its factorization.

991558855199 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90141714120.

The product of its digits is 262440000, while the sum is 74.

The spelling of 991558855199 in words is "nine hundred ninety-one billion, five hundred fifty-eight million, eight hundred fifty-five thousand, one hundred ninety-nine".