21004384 has 24 divisors (see below), whose sum is σ = 43786008. Its totient is φ = 9884160.

The previous prime is 21004351. The next prime is 21004387. The reversal of 21004384 is 48340012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004387) by changing a digit.

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, 18762 + ... + 19849.

It is an arithmetic number, because the mean of its divisors is an integer number (1824417).

Almost surely, 2^21004384 is an apocalyptic number.

It is an amenable number.

21004384 is an abundant number, since it is smaller than the sum of its proper divisors (22781624).

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

21004384 is a wasteful number, since it uses less digits than its factorization.

21004384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38638 (or 38630 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 21004384 is about 4583.0540036094. The cubic root of 21004384 is about 275.9116149112.

Adding to 21004384 its reverse (48340012), we get a palindrome (69344396).

The spelling of 21004384 in words is "twenty-one million, four thousand, three hundred eighty-four".