991309140 has 72 divisors (see below), whose sum is σ = 3016933920. Its totient is φ = 263473344.

The previous prime is 991309139. The next prime is 991309157. The reversal of 991309140 is 41903199.

991309140 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×991309140² = 1965387622095079200, which contains 22 as substring.

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 = 991309095 and 991309104.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 46291 + ... + 64229.

It is an arithmetic number, because the mean of its divisors is an integer number (41901860).

Almost surely, 2^991309140 is an apocalyptic number.

991309140 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 991309140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1508466960).

991309140 is an abundant number, since it is smaller than the sum of its proper divisors (2025624780).

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

991309140 is a wasteful number, since it uses less digits than its factorization.

991309140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18261 (or 18256 counting only the distinct ones).

The product of its (nonzero) digits is 8748, while the sum is 36.

The square root of 991309140 is about 31485.0621724017. The cubic root of 991309140 is about 997.0946135714.

The spelling of 991309140 in words is "nine hundred ninety-one million, three hundred nine thousand, one hundred forty".