21533265 has 24 divisors (see below), whose sum is σ = 40196520. Its totient is φ = 10600704.

The previous prime is 21533263. The next prime is 21533269. The reversal of 21533265 is 56233512.

It can be written as a sum of positive squares in 4 ways, for example, as 77841 + 21455424 = 279^2 + 4632^2 .

It is not a de Polignac number, because 21533265 - 2¹ = 21533263 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21533263) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17820 + ... + 18989.

It is an arithmetic number, because the mean of its divisors is an integer number (1674855).

Almost surely, 2^21533265 is an apocalyptic number.

It is an amenable number.

21533265 is a deficient number, since it is larger than the sum of its proper divisors (18663255).

21533265 is a wasteful number, since it uses less digits than its factorization.

21533265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36833 (or 36830 counting only the distinct ones).

The product of its digits is 5400, while the sum is 27.

The square root of 21533265 is about 4640.3949185387. The cubic root of 21533265 is about 278.2082226227.

Adding to 21533265 its reverse (56233512), we get a palindrome (77766777).

The spelling of 21533265 in words is "twenty-one million, five hundred thirty-three thousand, two hundred sixty-five".