81072012 has 96 divisors (see below), whose sum is σ = 230809600. Its totient is φ = 21632832.

The previous prime is 81072011. The next prime is 81072029. The reversal of 81072012 is 21027018.

It is a super-2 number, since 2×81072012² = 13145342259456288, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 81072012.

It is not an unprimeable number, because it can be changed into a prime (81072011) 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 31 ways as a sum of consecutive naturals, for example, 125763 + ... + 126405.

Almost surely, 2^81072012 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81072012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (115404800).

81072012 is an abundant number, since it is smaller than the sum of its proper divisors (149737588).

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

81072012 is a wasteful number, since it uses less digits than its factorization.

81072012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 755 (or 753 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 81072012 is about 9003.9997778765. Note that the first 3 decimals coincide. The cubic root of 81072012 is about 432.8030544416.

The spelling of 81072012 in words is "eighty-one million, seventy-two thousand, twelve".