20804 has 12 divisors (see below), whose sum is σ = 41664. Its totient is φ = 8904.

The previous prime is 20789. The next prime is 20807. The reversal of 20804 is 40802.

20804 is an admirable number.

It is a Harshad number since it is a multiple of its sum of digits (14).

It is not an unprimeable number, because it can be changed into a prime (20807) by changing a digit.

20804 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 344 + ... + 399.

It is an arithmetic number, because the mean of its divisors is an integer number (3472).

2²⁰⁸⁰⁴ is an apocalyptic number.

It is an amenable number.

20804 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20832).

20804 is a wasteful number, since it uses less digits than its factorization.

20804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 754 (or 752 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 20804 is about 144.2359178568. The cubic root of 20804 is about 27.5031401373.

The spelling of 20804 in words is "twenty thousand, eight hundred four".