9991438560 has 384 divisors, whose sum is σ = 38038170240. Its totient is φ = 2439217152.

The previous prime is 9991438559. The next prime is 9991438609. The reversal of 9991438560 is 658341999.

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

It is a junction number, because it is equal to n+sod(n) for n = 9991438497 and 9991438506.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2715442 + ... + 2719118.

It is an arithmetic number, because the mean of its divisors is an integer number (99057735).

Almost surely, 2^9991438560 is an apocalyptic number.

9991438560 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 9991438560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19019085120).

9991438560 is an abundant number, since it is smaller than the sum of its proper divisors (28046731680).

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

9991438560 is a wasteful number, since it uses less digits than its factorization.

9991438560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3755 (or 3741 counting only the distinct ones).

The product of its (nonzero) digits is 2099520, while the sum is 54.

The square root of 9991438560 is about 99957.1836337939. The cubic root of 9991438560 is about 2153.8196790414.

The spelling of 9991438560 in words is "nine billion, nine hundred ninety-one million, four hundred thirty-eight thousand, five hundred sixty".