81393757189 has 4 divisors (see below), whose sum is σ = 81752320224. Its totient is φ = 81035194156.

The previous prime is 81393757177. The next prime is 81393757267. The reversal of 81393757189 is 98175739318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81393757189 - 2⁹ = 81393756677 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81393757129) 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, 179281177 + ... + 179281630.

It is an arithmetic number, because the mean of its divisors is an integer number (20438080056).

Almost surely, 2^81393757189 is an apocalyptic number.

It is an amenable number.

81393757189 is a deficient number, since it is larger than the sum of its proper divisors (358563035).

81393757189 is a wasteful number, since it uses less digits than its factorization.

81393757189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358563034.

The product of its digits is 11430720, while the sum is 61.

The spelling of 81393757189 in words is "eighty-one billion, three hundred ninety-three million, seven hundred fifty-seven thousand, one hundred eighty-nine".