991920384 has 576 divisors, whose sum is σ = 3845990400. Its totient is φ = 244850688.

The previous prime is 991920373. The next prime is 991920389. The reversal of 991920384 is 483029199.

It is a tau number, because it is divible by the number of its divisors (576).

It is not an unprimeable number, because it can be changed into a prime (991920389) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 11950807 + ... + 11950889.

Almost surely, 2^991920384 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 991920384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1922995200).

991920384 is an abundant number, since it is smaller than the sum of its proper divisors (2854070016).

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

991920384 is a wasteful number, since it uses less digits than its factorization.

991920384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147 (or 127 counting only the distinct ones).

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

The square root of 991920384 is about 31494.7675654227. The cubic root of 991920384 is about 997.2995085773.

It can be divided in two parts, 9919 and 20384, that added together give a palindrome (30303).

The spelling of 991920384 in words is "nine hundred ninety-one million, nine hundred twenty thousand, three hundred eighty-four".