21004134205 has 4 divisors (see below), whose sum is σ = 25204961052. Its totient is φ = 16803307360.

The previous prime is 21004134163. The next prime is 21004134233. The reversal of 21004134205 is 50243140012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10473680281 + 10530453924 = 102341^2 + 102618^2 .

It is not a de Polignac number, because 21004134205 - 2¹¹ = 21004132157 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2100413416 + ... + 2100413425.

It is an arithmetic number, because the mean of its divisors is an integer number (6301240263).

Almost surely, 2^21004134205 is an apocalyptic number.

It is an amenable number.

21004134205 is a deficient number, since it is larger than the sum of its proper divisors (4200826847).

21004134205 is an equidigital number, since it uses as much as digits as its factorization.

21004134205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4200826846.

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

Adding to 21004134205 its reverse (50243140012), we get a palindrome (71247274217).

The spelling of 21004134205 in words is "twenty-one billion, four million, one hundred thirty-four thousand, two hundred five".