20904320 has 64 divisors (see below), whose sum is σ = 50673600. Its totient is φ = 8245248.

The previous prime is 20904319. The next prime is 20904337. The reversal of 20904320 is 2340902.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 20904292 and 20904301.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 56777 + ... + 57143.

It is an arithmetic number, because the mean of its divisors is an integer number (791775).

Almost surely, 2^20904320 is an apocalyptic number.

20904320 is a gapful number since it is divisible by the number (20) 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 20904320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25336800).

20904320 is an abundant number, since it is smaller than the sum of its proper divisors (29769280).

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

20904320 is an equidigital number, since it uses as much as digits as its factorization.

20904320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475 (or 463 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 20.

The square root of 20904320 is about 4572.1242327828. The cubic root of 20904320 is about 275.4727735300.

The spelling of 20904320 in words is "twenty million, nine hundred four thousand, three hundred twenty".