81158085385 has 16 divisors (see below), whose sum is σ = 105809379984. Its totient is φ = 59401746432.

The previous prime is 81158085383. The next prime is 81158085389. The reversal of 81158085385 is 58358085118.

It can be written as a sum of positive squares in 8 ways, for example, as 6412165776 + 74745919609 = 80076^2 + 273397^2 .

It is a cyclic number.

It is not a de Polignac number, because 81158085385 - 2¹ = 81158085383 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81158085383) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5517372 + ... + 5532061.

It is an arithmetic number, because the mean of its divisors is an integer number (6613086249).

Almost surely, 2^81158085385 is an apocalyptic number.

It is an amenable number.

81158085385 is a deficient number, since it is larger than the sum of its proper divisors (24651294599).

81158085385 is a wasteful number, since it uses less digits than its factorization.

81158085385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11049564.

The product of its (nonzero) digits is 1536000, while the sum is 52.

The spelling of 81158085385 in words is "eighty-one billion, one hundred fifty-eight million, eighty-five thousand, three hundred eighty-five".