991368 has 72 divisors (see below), whose sum is σ = 3134430. Its totient is φ = 282240.

The previous prime is 991357. The next prime is 991381. The reversal of 991368 is 863199.

It can be written as a sum of positive squares in only one way, i.e., 777924 + 213444 = 882^2 + 462^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×991368² = 1965621022848, which contains 22 as substring.

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

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

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991368.

It is an unprimeable number.

991368 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 3388 + ... + 3668.

2⁹⁹¹³⁶⁸ is an apocalyptic number.

991368 is a gapful number since it is divisible by the number (98) 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 991368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1567215).

991368 is an abundant number, since it is smaller than the sum of its proper divisors (2143062).

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

991368 is a wasteful number, since it uses less digits than its factorization.

991368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 307 (or 293 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 991368 is about 995.6746456549. The cubic root of 991368 is about 99.7114347687.

The spelling of 991368 in words is "nine hundred ninety-one thousand, three hundred sixty-eight".