81571305385 has 12 divisors (see below), whose sum is σ = 102326502852. Its totient is φ = 62419779488.

The previous prime is 81571305371. The next prime is 81571305401. The reversal of 81571305385 is 58350317518.

It can be written as a sum of positive squares in 2 ways, for example, as 41236206489 + 40335098896 = 203067^2 + 200836^2 .

It is not a de Polignac number, because 81571305385 - 2⁹ = 81571304873 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15417262 + ... + 15422551.

It is an arithmetic number, because the mean of its divisors is an integer number (8527208571).

Almost surely, 2^81571305385 is an apocalyptic number.

It is an amenable number.

81571305385 is a deficient number, since it is larger than the sum of its proper divisors (20755197467).

81571305385 is a wasteful number, since it uses less digits than its factorization.

81571305385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30839864 (or 30839841 counting only the distinct ones).

The product of its (nonzero) digits is 504000, while the sum is 46.

The spelling of 81571305385 in words is "eighty-one billion, five hundred seventy-one million, three hundred five thousand, three hundred eighty-five".