991088 has 20 divisors (see below), whose sum is σ = 2194800. Its totient is φ = 424704.

The previous prime is 991079. The next prime is 991091. The reversal of 991088 is 880199.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

991088 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4313 + ... + 4536.

It is an arithmetic number, because the mean of its divisors is an integer number (109740).

2⁹⁹¹⁰⁸⁸ is an apocalyptic number.

It is an amenable number.

991088 is an abundant number, since it is smaller than the sum of its proper divisors (1203712).

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

991088 is a wasteful number, since it uses less digits than its factorization.

991088 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8864 (or 8858 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 35.

The square root of 991088 is about 995.5340275450. The cubic root of 991088 is about 99.7020464519.

Subtracting from 991088 its reverse (880199), we obtain a square (110889 = 333²).

The spelling of 991088 in words is "nine hundred ninety-one thousand, eighty-eight".