81688859616 has 576 divisors, whose sum is σ = 285138040320. Its totient is φ = 20239994880.

The previous prime is 81688859591. The next prime is 81688859617. The reversal of 81688859616 is 61695888618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81688859617) 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 95 ways as a sum of consecutive naturals, for example, 194035086 + ... + 194035506.

It is an arithmetic number, because the mean of its divisors is an integer number (495031320).

Almost surely, 2^81688859616 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 81688859616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142569020160).

81688859616 is an abundant number, since it is smaller than the sum of its proper divisors (203449180704).

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

81688859616 is a wasteful number, since it uses less digits than its factorization.

81688859616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 647 (or 632 counting only the distinct ones).

The product of its digits is 39813120, while the sum is 66.

The spelling of 81688859616 in words is "eighty-one billion, six hundred eighty-eight million, eight hundred fifty-nine thousand, six hundred sixteen".