81387956608 has 128 divisors (see below), whose sum is σ = 189752509440. Its totient is φ = 34052659200.

The previous prime is 81387956591. The next prime is 81387956623. The reversal of 81387956608 is 80665978318.

It is a tau number, because it is divible by the number of its divisors (128).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6546238 + ... + 6558658.

It is an arithmetic number, because the mean of its divisors is an integer number (1482441480).

Almost surely, 2^81387956608 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81387956608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94876254720).

81387956608 is an abundant number, since it is smaller than the sum of its proper divisors (108364552832).

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

81387956608 is a wasteful number, since it uses less digits than its factorization.

81387956608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12616 (or 12604 counting only the distinct ones).

The product of its (nonzero) digits is 17418240, while the sum is 61.

The spelling of 81387956608 in words is "eighty-one billion, three hundred eighty-seven million, nine hundred fifty-six thousand, six hundred eight".