21604530 has 16 divisors (see below), whose sum is σ = 51850944. Its totient is φ = 5761200.

The previous prime is 21604529. The next prime is 21604579. The reversal of 21604530 is 3540612.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21604497 and 21604506.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 360046 + ... + 360105.

It is an arithmetic number, because the mean of its divisors is an integer number (3240684).

Almost surely, 2^21604530 is an apocalyptic number.

21604530 is an abundant number, since it is smaller than the sum of its proper divisors (30246414).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21604530 is a wasteful number, since it uses less digits than its factorization.

21604530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 720161.

The product of its (nonzero) digits is 720, while the sum is 21.

The square root of 21604530 is about 4648.0673403039. The cubic root of 21604530 is about 278.5147975424.

The spelling of 21604530 in words is "twenty-one million, six hundred four thousand, five hundred thirty".