991812 has 12 divisors (see below), whose sum is σ = 2314256. Its totient is φ = 330600.

The previous prime is 991811. The next prime is 991817. The reversal of 991812 is 218199.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 991812.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 991812.

It is not an unprimeable number, because it can be changed into a prime (991811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41314 + ... + 41337.

2⁹⁹¹⁸¹² is an apocalyptic number.

It is an amenable number.

991812 is an abundant number, since it is smaller than the sum of its proper divisors (1322444).

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

991812 is a wasteful number, since it uses less digits than its factorization.

991812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82658 (or 82656 counting only the distinct ones).

The product of its digits is 1296, while the sum is 30.

The square root of 991812 is about 995.8975850960. The cubic root of 991812 is about 99.7263183334.

The spelling of 991812 in words is "nine hundred ninety-one thousand, eight hundred twelve".