21224404 has 12 divisors (see below), whose sum is σ = 38423700. Its totient is φ = 10246208.

The previous prime is 21224389. The next prime is 21224431. The reversal of 21224404 is 40442212.

It can be written as a sum of positive squares in 2 ways, for example, as 13395600 + 7828804 = 3660^2 + 2798^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 91369 + ... + 91600.

It is an arithmetic number, because the mean of its divisors is an integer number (3201975).

Almost surely, 2^21224404 is an apocalyptic number.

It is an amenable number.

21224404 is a deficient number, since it is larger than the sum of its proper divisors (17199296).

21224404 is a wasteful number, since it uses less digits than its factorization.

21224404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183002 (or 183000 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 19.

The square root of 21224404 is about 4606.9951161250. The cubic root of 21224404 is about 276.8716578874.

Adding to 21224404 its reverse (40442212), we get a palindrome (61666616).

The spelling of 21224404 in words is "twenty-one million, two hundred twenty-four thousand, four hundred four".