81018974453785 has 4 divisors (see below), whose sum is σ = 97222769344548. Its totient is φ = 64815179563024.

The previous prime is 81018974453783. The next prime is 81018974453803. The reversal of 81018974453785 is 58735447981018.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 28485586421721 + 52533388032064 = 5337189^2 + 7247992^2 .

It is a cyclic number.

It is not a de Polignac number, because 81018974453785 - 2¹ = 81018974453783 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81018974453783) 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, 8101897445374 + ... + 8101897445383.

It is an arithmetic number, because the mean of its divisors is an integer number (24305692336137).

Almost surely, 2^{81018974453785} is an apocalyptic number.

It is an amenable number.

81018974453785 is a deficient number, since it is larger than the sum of its proper divisors (16203794890763).

81018974453785 is a wasteful number, since it uses less digits than its factorization.

81018974453785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16203794890762.

The product of its (nonzero) digits is 270950400, while the sum is 70.

The spelling of 81018974453785 in words is "eighty-one trillion, eighteen billion, nine hundred seventy-four million, four hundred fifty-three thousand, seven hundred eighty-five".