21003604521 has 8 divisors (see below), whose sum is σ = 28006755840. Its totient is φ = 14001428112.

The previous prime is 21003604423. The next prime is 21003604579. The reversal of 21003604521 is 12540630012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21003604521 - 2¹⁰ = 21003603497 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21003604491 and 21003604500.

It is not an unprimeable number, because it can be changed into a prime (21003606521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191881 + ... + 280758.

It is an arithmetic number, because the mean of its divisors is an integer number (3500844480).

Almost surely, 2^21003604521 is an apocalyptic number.

It is an amenable number.

21003604521 is a deficient number, since it is larger than the sum of its proper divisors (7003151319).

21003604521 is a wasteful number, since it uses less digits than its factorization.

21003604521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487455.

The product of its (nonzero) digits is 1440, while the sum is 24.

The spelling of 21003604521 in words is "twenty-one billion, three million, six hundred four thousand, five hundred twenty-one".