9991812 has 24 divisors (see below), whose sum is σ = 23531200. Its totient is φ = 3299616.

The previous prime is 9991811. The next prime is 9991837. The reversal of 9991812 is 2181999.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (9991811) 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, 2512 + ... + 5127.

Almost surely, 2^9991812 is an apocalyptic number.

It is an amenable number.

9991812 is an abundant number, since it is smaller than the sum of its proper divisors (13539388).

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

9991812 is a wasteful number, since it uses less digits than its factorization.

9991812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7755 (or 7753 counting only the distinct ones).

The product of its digits is 11664, while the sum is 39.

The square root of 9991812 is about 3160.9827585737. The cubic root of 9991812 is about 215.3846512428.

The spelling of 9991812 in words is "nine million, nine hundred ninety-one thousand, eight hundred twelve".