81558195139 has 4 divisors (see below), whose sum is σ = 81660527424. Its totient is φ = 81455862856.

The previous prime is 81558195137. The next prime is 81558195149. The reversal of 81558195139 is 93159185518.

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

It is a cyclic number.

It is not a de Polignac number, because 81558195139 - 2¹ = 81558195137 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81558195139.

It is not an unprimeable number, because it can be changed into a prime (81558195137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51164947 + ... + 51166540.

It is an arithmetic number, because the mean of its divisors is an integer number (20415131856).

Almost surely, 2^81558195139 is an apocalyptic number.

81558195139 is a deficient number, since it is larger than the sum of its proper divisors (102332285).

81558195139 is a wasteful number, since it uses less digits than its factorization.

81558195139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102332284.

The product of its digits is 1944000, while the sum is 55.

The spelling of 81558195139 in words is "eighty-one billion, five hundred fifty-eight million, one hundred ninety-five thousand, one hundred thirty-nine".