991811709120 has 112 divisors (see below), whose sum is σ = 3149549301600. Its totient is φ = 264437170176.

The previous prime is 991811709101. The next prime is 991811709197. The reversal of 991811709120 is 21907118199.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 991811709120.

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 in 15 ways as a sum of consecutive naturals, for example, 5628106 + ... + 5801654.

Almost surely, 2^991811709120 is an apocalyptic number.

It is an amenable number.

991811709120 is an abundant number, since it is smaller than the sum of its proper divisors (2157737592480).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991811709120 is a wasteful number, since it uses less digits than its factorization.

991811709120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179522 (or 179512 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 48.

The spelling of 991811709120 in words is "nine hundred ninety-one billion, eight hundred eleven million, seven hundred nine thousand, one hundred twenty".