81906912 has 72 divisors (see below), whose sum is σ = 234299520. Its totient is φ = 27141120.

The previous prime is 81906911. The next prime is 81906917. The reversal of 81906912 is 21960918.

It is a tau number, because it is divible by the number of its divisors (72).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81906911) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 54264 + ... + 55752.

It is an arithmetic number, because the mean of its divisors is an integer number (3254160).

Almost surely, 2^81906912 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 81906912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117149760).

81906912 is an abundant number, since it is smaller than the sum of its proper divisors (152392608).

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

81906912 is a wasteful number, since it uses less digits than its factorization.

81906912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1696 (or 1685 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 81906912 is about 9050.2437536234. The cubic root of 81906912 is about 434.2836883232.

The spelling of 81906912 in words is "eighty-one million, nine hundred six thousand, nine hundred twelve".