21224444 has 12 divisors (see below), whose sum is σ = 39097800. Its totient is φ = 10053648.

The previous prime is 21224431. The next prime is 21224447. The reversal of 21224444 is 44442212.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224447) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139559 + ... + 139710.

It is an arithmetic number, because the mean of its divisors is an integer number (3258150).

Almost surely, 2^21224444 is an apocalyptic number.

It is an amenable number.

21224444 is a deficient number, since it is larger than the sum of its proper divisors (17873356).

21224444 is a wasteful number, since it uses less digits than its factorization.

21224444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279292 (or 279290 counting only the distinct ones).

The product of its digits is 2048, while the sum is 23.

The square root of 21224444 is about 4606.9994573475. Note that the first 3 decimals coincide. The cubic root of 21224444 is about 276.8718318202.

Adding to 21224444 its reverse (44442212), we get a palindrome (65666656).

The spelling of 21224444 in words is "twenty-one million, two hundred twenty-four thousand, four hundred forty-four".