991291392 has 384 divisors, whose sum is σ = 3632428800. Its totient is φ = 260112384.

The previous prime is 991291387. The next prime is 991291397. The reversal of 991291392 is 293192199.

It is an interprime number because it is at equal distance from previous prime (991291387) and next prime (991291397).

It is a tau number, because it is divible by the number of its divisors (384).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (991291397) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5031838 + ... + 5032034.

It is an arithmetic number, because the mean of its divisors is an integer number (9459450).

Almost surely, 2^991291392 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 991291392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1816214400).

991291392 is an abundant number, since it is smaller than the sum of its proper divisors (2641137408).

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

991291392 is a wasteful number, since it uses less digits than its factorization.

991291392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248 (or 222 counting only the distinct ones).

The product of its digits is 78732, while the sum is 45.

The square root of 991291392 is about 31484.7803231974. The cubic root of 991291392 is about 997.0886630090.

The spelling of 991291392 in words is "nine hundred ninety-one million, two hundred ninety-one thousand, three hundred ninety-two".