81099912 has 32 divisors (see below), whose sum is σ = 203025600. Its totient is φ = 26996544.

The previous prime is 81099859. The next prime is 81099913. The reversal of 81099912 is 21999018.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81099913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20218 + ... + 23894.

It is an arithmetic number, because the mean of its divisors is an integer number (6344550).

Almost surely, 2^81099912 is an apocalyptic number.

It is an amenable number.

81099912 is an abundant number, since it is smaller than the sum of its proper divisors (121925688).

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

81099912 is a wasteful number, since it uses less digits than its factorization.

81099912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4605 (or 4601 counting only the distinct ones).

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

The square root of 81099912 is about 9005.5489560604. The cubic root of 81099912 is about 432.8526968110.

The spelling of 81099912 in words is "eighty-one million, ninety-nine thousand, nine hundred twelve".