21224565 has 16 divisors (see below), whose sum is σ = 37732800. Its totient is φ = 11319696.

The previous prime is 21224563. The next prime is 21224579. The reversal of 21224565 is 56542212.

It is not a de Polignac number, because 21224565 - 2¹ = 21224563 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21224563) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 78475 + ... + 78744.

It is an arithmetic number, because the mean of its divisors is an integer number (2358300).

Almost surely, 2^21224565 is an apocalyptic number.

It is an amenable number.

21224565 is a deficient number, since it is larger than the sum of its proper divisors (16508235).

21224565 is a wasteful number, since it uses less digits than its factorization.

21224565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157233 (or 157227 counting only the distinct ones).

The product of its digits is 4800, while the sum is 27.

The square root of 21224565 is about 4607.0125895205. The cubic root of 21224565 is about 276.8723579656.

Adding to 21224565 its reverse (56542212), we get a palindrome (77766777).

The spelling of 21224565 in words is "twenty-one million, two hundred twenty-four thousand, five hundred sixty-five".