991488880 has 20 divisors (see below), whose sum is σ = 2305211832. Its totient is φ = 396595520.

The previous prime is 991488833. The next prime is 991488887. The reversal of 991488880 is 88884199.

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991488887) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6196726 + ... + 6196885.

Almost surely, 2^991488880 is an apocalyptic number.

It is an amenable number.

991488880 is an abundant number, since it is smaller than the sum of its proper divisors (1313722952).

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

991488880 is a wasteful number, since it uses less digits than its factorization.

991488880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12393624 (or 12393618 counting only the distinct ones).

The product of its (nonzero) digits is 1327104, while the sum is 55.

The square root of 991488880 is about 31487.9164124907. The cubic root of 991488880 is about 997.1548729288.

The spelling of 991488880 in words is "nine hundred ninety-one million, four hundred eighty-eight thousand, eight hundred eighty".