81005312 has 36 divisors (see below), whose sum is σ = 163233840. Its totient is φ = 40117248.

The previous prime is 81005311. The next prime is 81005329. The reversal of 81005312 is 21350018.

It is not an unprimeable number, because it can be changed into a prime (81005311) 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, 26453 + ... + 29355.

Almost surely, 2^81005312 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 81005312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81616920).

81005312 is an abundant number, since it is smaller than the sum of its proper divisors (82228528).

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

81005312 is a wasteful number, since it uses less digits than its factorization.

81005312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3028 (or 3014 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 81005312 is about 9000.2951062729. The cubic root of 81005312 is about 432.6843291938.

The spelling of 81005312 in words is "eighty-one million, five thousand, three hundred twelve".