991913 has 8 divisors (see below), whose sum is σ = 1094856. Its totient is φ = 892800.

The previous prime is 991909. The next prime is 991927. The reversal of 991913 is 319199.

991913 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 196249 + 795664 = 443^2 + 892^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991913 - 2² = 991909 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 991913.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991913.

It is not an unprimeable number, because it can be changed into a prime (991943) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 398 + ... + 1463.

It is an arithmetic number, because the mean of its divisors is an integer number (136857).

2⁹⁹¹⁹¹³ is an apocalyptic number.

It is an amenable number.

991913 is a deficient number, since it is larger than the sum of its proper divisors (102943).

991913 is a wasteful number, since it uses less digits than its factorization.

991913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1915.

The product of its digits is 2187, while the sum is 32.

The square root of 991913 is about 995.9482918305. The cubic root of 991913 is about 99.7297033890.

The spelling of 991913 in words is "nine hundred ninety-one thousand, nine hundred thirteen".