991238040 has 256 divisors, whose sum is σ = 3768508800. Its totient is φ = 229588992.

The previous prime is 991237997. The next prime is 991238047. The reversal of 991238040 is 40832199.

991238040 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 991237986 and 991238004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991238047) 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, 236604 + ... + 240756.

Almost surely, 2^991238040 is an apocalyptic number.

991238040 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 991238040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1884254400).

991238040 is an abundant number, since it is smaller than the sum of its proper divisors (2777270760).

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

991238040 is a wasteful number, since it uses less digits than its factorization.

991238040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4203 (or 4193 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 36.

The square root of 991238040 is about 31483.9330452852. The cubic root of 991238040 is about 997.0707746836.

The spelling of 991238040 in words is "nine hundred ninety-one million, two hundred thirty-eight thousand, forty".