21165224 has 16 divisors (see below), whose sum is σ = 39930720. Its totient is φ = 10517040.

The previous prime is 21165197. The next prime is 21165227. The reversal of 21165224 is 42256112.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21165224.

It is not an unprimeable number, because it can be changed into a prime (21165227) 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 in 3 ways as a sum of consecutive naturals, for example, 6812 + ... + 9419.

It is an arithmetic number, because the mean of its divisors is an integer number (2495670).

Almost surely, 2^21165224 is an apocalyptic number.

It is an amenable number.

21165224 is a deficient number, since it is larger than the sum of its proper divisors (18765496).

21165224 is a wasteful number, since it uses less digits than its factorization.

21165224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16400 (or 16396 counting only the distinct ones).

The product of its digits is 960, while the sum is 23.

The square root of 21165224 is about 4600.5677910449. The cubic root of 21165224 is about 276.6140846185.

The spelling of 21165224 in words is "twenty-one million, one hundred sixty-five thousand, two hundred twenty-four".