20304 has 40 divisors (see below), whose sum is σ = 59520. Its totient is φ = 6624.

The previous prime is 20297. The next prime is 20323. The reversal of 20304 is 40302.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

20304 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 (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 409 + ... + 455.

It is an arithmetic number, because the mean of its divisors is an integer number (1488).

2²⁰³⁰⁴ is an apocalyptic number.

20304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29760).

20304 is an abundant number, since it is smaller than the sum of its proper divisors (39216).

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

20304 is a wasteful number, since it uses less digits than its factorization.

20304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64 (or 52 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 9.

The square root of 20304 is about 142.4921050445. The cubic root of 20304 is about 27.2810156627.

Adding to 20304 its reverse (40302), we get a palindrome (60606).

It can be divided in two parts, 20 and 304, that added together give a square (324 = 18²).

The spelling of 20304 in words is "twenty thousand, three hundred four", and thus it is an iban number.