81930317656 has 64 divisors (see below), whose sum is σ = 173561564160. Its totient is φ = 35935200000.

The previous prime is 81930317653. The next prime is 81930317681. The reversal of 81930317656 is 65671303918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81930317653) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 154156 + ... + 433156.

It is an arithmetic number, because the mean of its divisors is an integer number (2711899440).

Almost surely, 2^81930317656 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 81930317656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86780782080).

81930317656 is an abundant number, since it is smaller than the sum of its proper divisors (91631246504).

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

81930317656 is a wasteful number, since it uses less digits than its factorization.

81930317656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279136 (or 279132 counting only the distinct ones).

The product of its (nonzero) digits is 816480, while the sum is 49.

The spelling of 81930317656 in words is "eighty-one billion, nine hundred thirty million, three hundred seventeen thousand, six hundred fifty-six".