81000012 has 12 divisors (see below), whose sum is σ = 189000056. Its totient is φ = 27000000.

The previous prime is 81000001. The next prime is 81000013. The reversal of 81000012 is 21000018.

It is a happy number.

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

It is a super-2 number, since 2×81000012² = 13122003888000288, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12), and also a Moran number because the ratio is a prime number: 6750001 = 81000012 / (8 + 1 + 0 + 0 + 0 + 0 + 1 + 2).

It is not an unprimeable number, because it can be changed into a prime (81000013) 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, 3374989 + ... + 3375012.

Almost surely, 2^81000012 is an apocalyptic number.

It is an amenable number.

81000012 is an abundant number, since it is smaller than the sum of its proper divisors (108000044).

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

81000012 is a wasteful number, since it uses less digits than its factorization.

81000012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6750008 (or 6750006 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 81000012 is about 9000.0006666666. Note that the first 3 decimals coincide. The cubic root of 81000012 is about 432.6748924589.

Subtracting from 81000012 its sum of digits (12), we obtain a square (81000000 = 9000²).

The spelling of 81000012 in words is "eighty-one million, twelve", and thus it is an aban number and an uban number.