991992 has 16 divisors (see below), whose sum is σ = 2480040. Its totient is φ = 330656.

The previous prime is 991987. The next prime is 991999. The reversal of 991992 is 299199.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 991992.

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 991992.

It is not an unprimeable number, because it can be changed into a prime (991999) by changing a digit.

991992 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 (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20643 + ... + 20690.

2⁹⁹¹⁹⁹² is an apocalyptic number.

It is an amenable number.

991992 is an abundant number, since it is smaller than the sum of its proper divisors (1488048).

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

991992 is a wasteful number, since it uses less digits than its factorization.

991992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41342 (or 41338 counting only the distinct ones).

The product of its digits is 13122, while the sum is 39.

The square root of 991992 is about 995.9879517344. The cubic root of 991992 is about 99.7323509456.

It can be divided in two parts, 9919 and 92, that added together give a triangular number (10011 = T₁₄₁).

The spelling of 991992 in words is "nine hundred ninety-one thousand, nine hundred ninety-two".