21604522 has 16 divisors (see below), whose sum is σ = 33487272. Its totient is φ = 10445760.

The previous prime is 21604487. The next prime is 21604523. The reversal of 21604522 is 22540612.

It can be written as a sum of positive squares in 4 ways, for example, as 17648401 + 3956121 = 4201^2 + 1989^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21604493 and 21604502.

It is not an unprimeable number, because it can be changed into a 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 in 7 ways as a sum of consecutive naturals, for example, 12588 + ... + 14200.

Almost surely, 2^21604522 is an apocalyptic number.

21604522 is a deficient number, since it is larger than the sum of its proper divisors (11882750).

21604522 is a wasteful number, since it uses less digits than its factorization.

21604522 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1833.

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21604522 is about 4648.0664797311. The cubic root of 21604522 is about 278.5147631651.

The spelling of 21604522 in words is "twenty-one million, six hundred four thousand, five hundred twenty-two".