81004664 has 32 divisors (see below), whose sum is σ = 164881920. Its totient is φ = 37086336.

The previous prime is 81004663. The next prime is 81004667. The reversal of 81004664 is 46640018.

It is a hoax number, since the sum of its digits (29) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81004661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10142 + ... + 16274.

It is an arithmetic number, because the mean of its divisors is an integer number (5152560).

Almost surely, 2^81004664 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 81004664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82440960).

81004664 is an abundant number, since it is smaller than the sum of its proper divisors (83877256).

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

81004664 is a wasteful number, since it uses less digits than its factorization.

81004664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6279 (or 6275 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 29.

The square root of 81004664 is about 9000.2591073813. The cubic root of 81004664 is about 432.6831754415.

The spelling of 81004664 in words is "eighty-one million, four thousand, six hundred sixty-four".