81647108915 has 4 divisors (see below), whose sum is σ = 97976530704. Its totient is φ = 65317687128.

The previous prime is 81647108911. The next prime is 81647108927. The reversal of 81647108915 is 51980174618.

It is a happy number.

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 81647108915 - 2² = 81647108911 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81647108911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8164710887 + ... + 8164710896.

It is an arithmetic number, because the mean of its divisors is an integer number (24494132676).

Almost surely, 2^81647108915 is an apocalyptic number.

81647108915 is a deficient number, since it is larger than the sum of its proper divisors (16329421789).

81647108915 is a wasteful number, since it uses less digits than its factorization.

81647108915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16329421788.

The product of its (nonzero) digits is 483840, while the sum is 50.

The spelling of 81647108915 in words is "eighty-one billion, six hundred forty-seven million, one hundred eight thousand, nine hundred fifteen".