9991423008 has 576 divisors, whose sum is σ = 36624752640. Its totient is φ = 2634508800.

The previous prime is 9991423007. The next prime is 9991423019. The reversal of 9991423008 is 8003241999.

It is not an unprimeable number, because it can be changed into a prime (9991423007) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 30185403 + ... + 30185733.

It is an arithmetic number, because the mean of its divisors is an integer number (63584640).

Almost surely, 2^9991423008 is an apocalyptic number.

9991423008 is a gapful number since it is divisible by the number (98) 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 9991423008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18312376320).

9991423008 is an abundant number, since it is smaller than the sum of its proper divisors (26633329632).

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

9991423008 is a wasteful number, since it uses less digits than its factorization.

9991423008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 418 (or 397 counting only the distinct ones).

The product of its (nonzero) digits is 139968, while the sum is 45.

The square root of 9991423008 is about 99957.1058404554. The cubic root of 9991423008 is about 2153.8185615440.

The spelling of 9991423008 in words is "nine billion, nine hundred ninety-one million, four hundred twenty-three thousand, eight".