21223404 has 48 divisors (see below), whose sum is σ = 56377440. Its totient is φ = 6900480.

The previous prime is 21223403. The next prime is 21223409. The reversal of 21223404 is 40432212.

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

It is not an unprimeable number, because it can be changed into a prime (21223403) 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, 2032 + ... + 6824.

It is an arithmetic number, because the mean of its divisors is an integer number (1174530).

Almost surely, 2^21223404 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 21223404, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28188720).

21223404 is an abundant number, since it is smaller than the sum of its proper divisors (35154036).

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

21223404 is a wasteful number, since it uses less digits than its factorization.

21223404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4847 (or 4839 counting only the distinct ones).

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

The square root of 21223404 is about 4606.8865842345. The cubic root of 21223404 is about 276.8673094967.

Adding to 21223404 its reverse (40432212), we get a palindrome (61655616).

The spelling of 21223404 in words is "twenty-one million, two hundred twenty-three thousand, four hundred four".