21530289 has 16 divisors (see below), whose sum is σ = 32082624. Its totient is φ = 12729600.

The previous prime is 21530281. The next prime is 21530291. The reversal of 21530289 is 98203512.

It is a happy number.

It is not a de Polignac number, because 21530289 - 2³ = 21530281 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21530281) 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, 6604 + ... + 9309.

It is an arithmetic number, because the mean of its divisors is an integer number (2005164).

Almost surely, 2^21530289 is an apocalyptic number.

It is an amenable number.

21530289 is a deficient number, since it is larger than the sum of its proper divisors (10552335).

21530289 is a wasteful number, since it uses less digits than its factorization.

21530289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15968.

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 21530289 is about 4640.0742450957. The cubic root of 21530289 is about 278.1954054641.

The spelling of 21530289 in words is "twenty-one million, five hundred thirty thousand, two hundred eighty-nine".