21044430 has 96 divisors (see below), whose sum is σ = 61832160. Its totient is φ = 4919040.

The previous prime is 21044423. The next prime is 21044431. The reversal of 21044430 is 3444012.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21044431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 28344 + ... + 29076.

It is an arithmetic number, because the mean of its divisors is an integer number (644085).

Almost surely, 2^21044430 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21044430, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30916080).

21044430 is an abundant number, since it is smaller than the sum of its proper divisors (40787730).

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

21044430 is a wasteful number, since it uses less digits than its factorization.

21044430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 786 (or 783 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21044430 is about 4587.4208440037. The cubic root of 21044430 is about 276.0868504242.

Adding to 21044430 its reverse (3444012), we get a palindrome (24488442).

The spelling of 21044430 in words is "twenty-one million, forty-four thousand, four hundred thirty".