991173960 has 384 divisors, whose sum is σ = 3931200000. Its totient is φ = 216082944.

The previous prime is 991173949. The next prime is 991173961. The reversal of 991173960 is 69371199.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991173961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2839866 + ... + 2840214.

It is an arithmetic number, because the mean of its divisors is an integer number (10237500).

Almost surely, 2^991173960 is an apocalyptic number.

991173960 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991173960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1965600000).

991173960 is an abundant number, since it is smaller than the sum of its proper divisors (2940026040).

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

991173960 is a wasteful number, since it uses less digits than its factorization.

991173960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410 (or 389 counting only the distinct ones).

The product of its (nonzero) digits is 91854, while the sum is 45.

The square root of 991173960 is about 31482.9153669097. The cubic root of 991173960 is about 997.0492885322.

The spelling of 991173960 in words is "nine hundred ninety-one million, one hundred seventy-three thousand, nine hundred sixty".