991079040 has 256 divisors, whose sum is σ = 3709797120. Its totient is φ = 220299264.

The previous prime is 991079009. The next prime is 991079041. The reversal of 991079040 is 40970199.

It is a self number, because there is not a number n which added to its sum of digits gives 991079040.

It is not an unprimeable number, because it can be changed into a prime (991079041) 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, 496284 + ... + 498276.

It is an arithmetic number, because the mean of its divisors is an integer number (14491395).

Almost surely, 2^991079040 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 991079040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1854898560).

991079040 is an abundant number, since it is smaller than the sum of its proper divisors (2718718080).

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

991079040 is a wasteful number, since it uses less digits than its factorization.

991079040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2059 (or 2047 counting only the distinct ones).

The product of its (nonzero) digits is 20412, while the sum is 39.

The square root of 991079040 is about 31481.4078465370. The cubic root of 991079040 is about 997.0174599654.

The spelling of 991079040 in words is "nine hundred ninety-one million, seventy-nine thousand, forty".