21912224 has 12 divisors (see below), whose sum is σ = 43139754. Its totient is φ = 10956096.

The previous prime is 21912221. The next prime is 21912229. The reversal of 21912224 is 42221912.

It can be written as a sum of positive squares in only one way, i.e., 15460624 + 6451600 = 3932^2 + 2540^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21912224.

It is not an unprimeable number, because it can be changed into a prime (21912221) 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 as a sum of consecutive naturals, namely, 342347 + ... + 342410.

Almost surely, 2^21912224 is an apocalyptic number.

It is an amenable number.

21912224 is a deficient number, since it is larger than the sum of its proper divisors (21227530).

21912224 is an equidigital number, since it uses as much as digits as its factorization.

21912224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 684767 (or 684759 counting only the distinct ones).

The product of its digits is 576, while the sum is 23.

The square root of 21912224 is about 4681.0494549834. The cubic root of 21912224 is about 279.8307821076.

It can be divided in two parts, 2191 and 2224, that multiplied together give a palindrome (4872784).

The spelling of 21912224 in words is "twenty-one million, nine hundred twelve thousand, two hundred twenty-four".