21530441 has 6 divisors (see below), whose sum is σ = 22299342. Its totient is φ = 20787200.

The previous prime is 21530413. The next prime is 21530447. The reversal of 21530441 is 14403512.

It can be written as a sum of positive squares in 3 ways, for example, as 11155600 + 10374841 = 3340^2 + 3221^2 .

It is not a de Polignac number, because 21530441 - 2¹⁸ = 21268297 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530447) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11960 + ... + 13641.

It is an arithmetic number, because the mean of its divisors is an integer number (3716557).

Almost surely, 2^21530441 is an apocalyptic number.

It is an amenable number.

21530441 is a deficient number, since it is larger than the sum of its proper divisors (768901).

21530441 is an equidigital number, since it uses as much as digits as its factorization.

21530441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25659 (or 25630 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21530441 is about 4640.0906241150. The cubic root of 21530441 is about 278.1960601326.

Adding to 21530441 its reverse (14403512), we get a palindrome (35933953).

The spelling of 21530441 in words is "twenty-one million, five hundred thirty thousand, four hundred forty-one".