991938 has 16 divisors (see below), whose sum is σ = 2048256. Its totient is φ = 319920.

The previous prime is 991931. The next prime is 991943. The reversal of 991938 is 839199.

It is a junction number, because it is equal to n+sod(n) for n = 991896 and 991905.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991938.

It is not an unprimeable number, because it can be changed into a prime (991931) by changing a digit.

991938 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2481 + ... + 2852.

It is an arithmetic number, because the mean of its divisors is an integer number (128016).

2⁹⁹¹⁹³⁸ is an apocalyptic number.

991938 is an abundant number, since it is smaller than the sum of its proper divisors (1056318).

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

991938 is a wasteful number, since it uses less digits than its factorization.

991938 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5369.

The product of its digits is 17496, while the sum is 39.

The square root of 991938 is about 995.9608426038. The cubic root of 991938 is about 99.7305412386.

The spelling of 991938 in words is "nine hundred ninety-one thousand, nine hundred thirty-eight".