21222224 has 10 divisors (see below), whose sum is σ = 41118090. Its totient is φ = 10611104.

The previous prime is 21222211. The next prime is 21222251. The reversal of 21222224 is 42222212.

It can be written as a sum of positive squares in only one way, i.e., 17909824 + 3312400 = 4232^2 + 1820^2 .

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

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 663179 + ... + 663210.

It is an arithmetic number, because the mean of its divisors is an integer number (4111809).

Almost surely, 2^21222224 is an apocalyptic number.

It is an amenable number.

21222224 is a deficient number, since it is larger than the sum of its proper divisors (19895866).

21222224 is a wasteful number, since it uses less digits than its factorization.

21222224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1326397 (or 1326391 counting only the distinct ones).

The product of its digits is 256, while the sum is 17.

The square root of 21222224 is about 4606.7585133150. The cubic root of 21222224 is about 276.8621782199.

Adding to 21222224 its reverse (42222212), we get a palindrome (63444436).

The spelling of 21222224 in words is "twenty-one million, two hundred twenty-two thousand, two hundred twenty-four".