81013572 has 36 divisors (see below), whose sum is σ = 210322476. Its totient is φ = 26274240.

The previous prime is 81013547. The next prime is 81013573. The reversal of 81013572 is 27531018.

81013572 is a `hidden beast` number, since 81 + 0 + 13 + 572 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 60000516 + 21013056 = 7746^2 + 4584^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (81013573) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29079 + ... + 31742.

It is an arithmetic number, because the mean of its divisors is an integer number (5842291).

Almost surely, 2^81013572 is an apocalyptic number.

It is an amenable number.

81013572 is an abundant number, since it is smaller than the sum of its proper divisors (129308904).

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

81013572 is a wasteful number, since it uses less digits than its factorization.

81013572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60868 (or 60863 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 27.

The square root of 81013572 is about 9000.7539684184. The cubic root of 81013572 is about 432.6990354354.

The spelling of 81013572 in words is "eighty-one million, thirteen thousand, five hundred seventy-two".