81910656 has 128 divisors (see below), whose sum is σ = 244922400. Its totient is φ = 26947584.

The previous prime is 81910651. The next prime is 81910667. The reversal of 81910656 is 65601918.

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

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 81910656.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81910651) 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, 473386 + ... + 473558.

Almost surely, 2^81910656 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 81910656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122461200).

81910656 is an abundant number, since it is smaller than the sum of its proper divisors (163011744).

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

81910656 is a wasteful number, since it uses less digits than its factorization.

81910656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333 (or 315 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 81910656 is about 9050.4505965173. The cubic root of 81910656 is about 434.2903053202.

The spelling of 81910656 in words is "eighty-one million, nine hundred ten thousand, six hundred fifty-six".