991940 has 12 divisors (see below), whose sum is σ = 2083116. Its totient is φ = 396768.

The previous prime is 991931. The next prime is 991943. The reversal of 991940 is 49199.

It can be written as a sum of positive squares in 2 ways, for example, as 174724 + 817216 = 418^2 + 904^2 .

It is a junction number, because it is equal to n+sod(n) for n = 991897 and 991906.

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

991940 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 3 ways as a sum of consecutive naturals, for example, 24779 + ... + 24818.

It is an arithmetic number, because the mean of its divisors is an integer number (173593).

2⁹⁹¹⁹⁴⁰ is an apocalyptic number.

It is an amenable number.

991940 is an abundant number, since it is smaller than the sum of its proper divisors (1091176).

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

991940 is a wasteful number, since it uses less digits than its factorization.

991940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49606 (or 49604 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 991940 is about 995.9618466588. The cubic root of 991940 is about 99.7306082659.

The spelling of 991940 in words is "nine hundred ninety-one thousand, nine hundred forty".