81804 has 24 divisors (see below), whose sum is σ = 202608. Its totient is φ = 25600.

The previous prime is 81799. The next prime is 81817. The reversal of 81804 is 40818.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4 + ... + 404.

It is an arithmetic number, because the mean of its divisors is an integer number (8442).

2⁸¹⁸⁰⁴ 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 81804, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101304).

81804 is an abundant number, since it is smaller than the sum of its proper divisors (120804).

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

81804 is a wasteful number, since it uses less digits than its factorization.

81804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425 (or 423 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 81804 is about 286.0139856720. The cubic root of 81804 is about 43.4101726740.

The spelling of 81804 in words is "eighty-one thousand, eight hundred four".