21224144 has 20 divisors (see below), whose sum is σ = 41205696. Its totient is φ = 10590432.

The previous prime is 21224141. The next prime is 21224149. The reversal of 21224144 is 44142212.

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 (21224141) 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, 9257 + ... + 11319.

Almost surely, 2^21224144 is an apocalyptic number.

It is an amenable number.

21224144 is a deficient number, since it is larger than the sum of its proper divisors (19981552).

21224144 is a wasteful number, since it uses less digits than its factorization.

21224144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2714 (or 2708 counting only the distinct ones).

The product of its digits is 512, while the sum is 20.

The square root of 21224144 is about 4606.9668980795. The cubic root of 21224144 is about 276.8705273190.

Adding to 21224144 its reverse (44142212), we get a palindrome (65366356).

The spelling of 21224144 in words is "twenty-one million, two hundred twenty-four thousand, one hundred forty-four".