991518 has 32 divisors (see below), whose sum is σ = 2201472. Its totient is φ = 295200.

The previous prime is 991511. The next prime is 991531. The reversal of 991518 is 815199.

991518 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 (33).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991518.

It is not an unprimeable number, because it can be changed into a prime (991511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5388 + ... + 5568.

It is an arithmetic number, because the mean of its divisors is an integer number (68796).

2⁹⁹¹⁵¹⁸ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991518, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1100736).

991518 is an abundant number, since it is smaller than the sum of its proper divisors (1209954).

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

991518 is a wasteful number, since it uses less digits than its factorization.

991518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280.

The product of its digits is 3240, while the sum is 33.

The square root of 991518 is about 995.7499686166. The cubic root of 991518 is about 99.7164634970.

The spelling of 991518 in words is "nine hundred ninety-one thousand, five hundred eighteen".