81305916768 has 36 divisors (see below), whose sum is σ = 231213701628. Its totient is φ = 27101972160.

The previous prime is 81305916751. The next prime is 81305916883. The reversal of 81305916768 is 86761950318.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×81305916768² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 141155818 + ... + 141156393.

It is an arithmetic number, because the mean of its divisors is an integer number (6422602823).

Almost surely, 2^81305916768 is an apocalyptic number.

It is an amenable number.

81305916768 is an abundant number, since it is smaller than the sum of its proper divisors (149907784860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81305916768 is a wasteful number, since it uses less digits than its factorization.

81305916768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 282312227 (or 282312216 counting only the distinct ones).

The product of its (nonzero) digits is 2177280, while the sum is 54.

The spelling of 81305916768 in words is "eighty-one billion, three hundred five million, nine hundred sixteen thousand, seven hundred sixty-eight".