81573705 has 12 divisors (see below), whose sum is σ = 141394500. Its totient is φ = 43505952.

The previous prime is 81573703. The next prime is 81573719. The reversal of 81573705 is 50737518.

81573705 is a `hidden beast` number, since 81 + 573 + 7 + 0 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 50168889 + 31404816 = 7083^2 + 5604^2 .

It is not a de Polignac number, because 81573705 - 2¹ = 81573703 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81573705.

It is not an unprimeable number, because it can be changed into a prime (81573703) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 906330 + ... + 906419.

It is an arithmetic number, because the mean of its divisors is an integer number (11782875).

Almost surely, 2^81573705 is an apocalyptic number.

It is an amenable number.

81573705 is a deficient number, since it is larger than the sum of its proper divisors (59820795).

81573705 is a wasteful number, since it uses less digits than its factorization.

81573705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1812760 (or 1812757 counting only the distinct ones).

The product of its (nonzero) digits is 29400, while the sum is 36.

The square root of 81573705 is about 9031.8162625244. The cubic root of 81573705 is about 433.6939821408.

The spelling of 81573705 in words is "eighty-one million, five hundred seventy-three thousand, seven hundred five".