21204211605 has 64 divisors (see below), whose sum is σ = 36299404800. Its totient is φ = 10532560896.

The previous prime is 21204211591. The next prime is 21204211663. The reversal of 21204211605 is 50611240212.

It is not a de Polignac number, because 21204211605 - 2⁶ = 21204211541 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 11891544 + ... + 11893326.

It is an arithmetic number, because the mean of its divisors is an integer number (567178200).

Almost surely, 2^21204211605 is an apocalyptic number.

It is an amenable number.

21204211605 is a deficient number, since it is larger than the sum of its proper divisors (15095193195).

21204211605 is a wasteful number, since it uses less digits than its factorization.

21204211605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2270.

The product of its (nonzero) digits is 960, while the sum is 24.

Adding to 21204211605 its reverse (50611240212), we get a palindrome (71815451817).

The spelling of 21204211605 in words is "twenty-one billion, two hundred four million, two hundred eleven thousand, six hundred five".