81190718005 has 4 divisors (see below), whose sum is σ = 97428861612. Its totient is φ = 64952574400.

The previous prime is 81190718003. The next prime is 81190718023. The reversal of 81190718005 is 50081709118.

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 39010595121 + 42180122884 = 197511^2 + 205378^2 .

It is not a de Polignac number, because 81190718005 - 2¹ = 81190718003 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81190718003) 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 3 ways as a sum of consecutive naturals, for example, 8119071796 + ... + 8119071805.

It is an arithmetic number, because the mean of its divisors is an integer number (24357215403).

Almost surely, 2^81190718005 is an apocalyptic number.

It is an amenable number.

81190718005 is a deficient number, since it is larger than the sum of its proper divisors (16238143607).

81190718005 is a wasteful number, since it uses less digits than its factorization.

81190718005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16238143606.

The product of its (nonzero) digits is 20160, while the sum is 40.

The spelling of 81190718005 in words is "eighty-one billion, one hundred ninety million, seven hundred eighteen thousand, five".