81955719865 has 32 divisors (see below), whose sum is σ = 100032641280. Its totient is φ = 64450636800.

The previous prime is 81955719847. The next prime is 81955719893. The reversal of 81955719865 is 56891755918.

It is not a de Polignac number, because 81955719865 - 2⁹ = 81955719353 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81955719797 and 81955719806.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 95630517 + ... + 95631373.

It is an arithmetic number, because the mean of its divisors is an integer number (3126020040).

Almost surely, 2^81955719865 is an apocalyptic number.

It is an amenable number.

81955719865 is a deficient number, since it is larger than the sum of its proper divisors (18076921415).

81955719865 is a wasteful number, since it uses less digits than its factorization.

81955719865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1953.

The product of its digits is 27216000, while the sum is 64.

The spelling of 81955719865 in words is "eighty-one billion, nine hundred fifty-five million, seven hundred nineteen thousand, eight hundred sixty-five".