21604529 has 2 divisors, whose sum is σ = 21604530. Its totient is φ = 21604528.

The previous prime is 21604523. The next prime is 21604579. The reversal of 21604529 is 92540612.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21603904 + 625 = 4648^2 + 25^2 .

It is a cyclic number.

It is not a de Polignac number, because 21604529 - 2²⁴ = 4827313 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21604523) by changing a digit.

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 as a sum of consecutive naturals, namely, 10802264 + 10802265.

It is an arithmetic number, because the mean of its divisors is an integer number (10802265).

Almost surely, 2^21604529 is an apocalyptic number.

It is an amenable number.

21604529 is a deficient number, since it is larger than the sum of its proper divisors (1).

21604529 is an equidigital number, since it uses as much as digits as its factorization.

21604529 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 21604529 is about 4648.0672327323. The cubic root of 21604529 is about 278.5147932452.

The spelling of 21604529 in words is "twenty-one million, six hundred four thousand, five hundred twenty-nine".