21344904 has 128 divisors (see below), whose sum is σ = 71424000. Its totient is φ = 5769792.

The previous prime is 21344903. The next prime is 21344929. The reversal of 21344904 is 40944312.

21344904 is a `hidden beast` number, since 213 + 449 + 0 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21344903) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28357 + ... + 29099.

It is an arithmetic number, because the mean of its divisors is an integer number (558000).

Almost surely, 2^21344904 is an apocalyptic number.

21344904 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 21344904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35712000).

21344904 is an abundant number, since it is smaller than the sum of its proper divisors (50079096).

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

21344904 is a wasteful number, since it uses less digits than its factorization.

21344904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 784 (or 774 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 21344904 is about 4620.0545451326. The cubic root of 21344904 is about 277.3946422540.

The spelling of 21344904 in words is "twenty-one million, three hundred forty-four thousand, nine hundred four".