81065664 has 112 divisors (see below), whose sum is σ = 244083840. Its totient is φ = 26369280.

The previous prime is 81065659. The next prime is 81065669. The reversal of 81065664 is 46656018.

It is an interprime number because it is at equal distance from previous prime (81065659) and next prime (81065669).

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

It is not an unprimeable number, because it can be changed into a prime (81065669) 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 15 ways as a sum of consecutive naturals, for example, 73759 + ... + 74849.

It is an arithmetic number, because the mean of its divisors is an integer number (2179320).

Almost surely, 2^81065664 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 81065664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122041920).

81065664 is an abundant number, since it is smaller than the sum of its proper divisors (163018176).

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

81065664 is a wasteful number, since it uses less digits than its factorization.

81065664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1155 (or 1139 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 81065664 is about 9003.6472609715. The cubic root of 81065664 is about 432.7917578777.

The spelling of 81065664 in words is "eighty-one million, sixty-five thousand, six hundred sixty-four".