991865088 has 180 divisors, whose sum is σ = 3054946048. Its totient is φ = 319749120.

The previous prime is 991865033. The next prime is 991865099. The reversal of 991865088 is 880568199.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

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 19 ways as a sum of consecutive naturals, for example, 642045 + ... + 643587.

Almost surely, 2^991865088 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991865088, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1527473024).

991865088 is an abundant number, since it is smaller than the sum of its proper divisors (2063080960).

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

991865088 is a wasteful number, since it uses less digits than its factorization.

991865088 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1602 (or 1579 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 54.

The square root of 991865088 is about 31493.8896930817. The cubic root of 991865088 is about 997.2809762773.

The spelling of 991865088 in words is "nine hundred ninety-one million, eight hundred sixty-five thousand, eighty-eight".