21004400205 has 12 divisors (see below), whose sum is σ = 36407627100. Its totient is φ = 11202346752.

The previous prime is 21004400203. The next prime is 21004400279. The reversal of 21004400205 is 50200440012.

21004400205 is a `hidden beast` number, since 21 + 0 + 0 + 440 + 0 + 205 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 12875213961 + 8129186244 = 113469^2 + 90162^2 .

It is not a de Polignac number, because 21004400205 - 2¹ = 21004400203 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004400203) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 233382180 + ... + 233382269.

It is an arithmetic number, because the mean of its divisors is an integer number (3033968925).

Almost surely, 2^21004400205 is an apocalyptic number.

It is an amenable number.

21004400205 is a deficient number, since it is larger than the sum of its proper divisors (15403226895).

21004400205 is a wasteful number, since it uses less digits than its factorization.

21004400205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 466764460 (or 466764457 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

Adding to 21004400205 its reverse (50200440012), we get a palindrome (71204840217).

The spelling of 21004400205 in words is "twenty-one billion, four million, four hundred thousand, two hundred five".