81105920 has 176 divisors, whose sum is σ = 232670208. Its totient is φ = 26542080.

The previous prime is 81105917. The next prime is 81105931. The reversal of 81105920 is 2950118.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 81105920.

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, 1111004 + ... + 1111076.

Almost surely, 2^81105920 is an apocalyptic number.

81105920 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81105920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116335104).

81105920 is an abundant number, since it is smaller than the sum of its proper divisors (151564288).

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

81105920 is a wasteful number, since it uses less digits than its factorization.

81105920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 118 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 81105920 is about 9005.8825219964. The cubic root of 81105920 is about 432.8633853339.

The spelling of 81105920 in words is "eighty-one million, one hundred five thousand, nine hundred twenty".