21440804 has 48 divisors (see below), whose sum is σ = 47523840. Its totient is φ = 8220960.

The previous prime is 21440803. The next prime is 21440821. The reversal of 21440804 is 40804412.

It is a self number, because there is not a number n which added to its sum of digits gives 21440804.

It is not an unprimeable number, because it can be changed into a prime (21440801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20117 + ... + 21155.

It is an arithmetic number, because the mean of its divisors is an integer number (990080).

Almost surely, 2^21440804 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21440804, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23761920).

21440804 is an abundant number, since it is smaller than the sum of its proper divisors (26083036).

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

21440804 is a wasteful number, since it uses less digits than its factorization.

21440804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1128 (or 1126 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 23.

The square root of 21440804 is about 4630.4215790790. The cubic root of 21440804 is about 277.8094548527.

The spelling of 21440804 in words is "twenty-one million, four hundred forty thousand, eight hundred four".