21104521205205 has 32 divisors (see below), whose sum is σ = 34012907368704. Its totient is φ = 11174103553536.

The previous prime is 21104521205177. The next prime is 21104521205231. The reversal of 21104521205205 is 50250212540112.

It is not a de Polignac number, because 21104521205205 - 2⁷ = 21104521205077 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6463537 + ... + 9164406.

It is an arithmetic number, because the mean of its divisors is an integer number (1062903355272).

Almost surely, 2^{21104521205205} is an apocalyptic number.

It is an amenable number.

21104521205205 is a deficient number, since it is larger than the sum of its proper divisors (12908386163499).

21104521205205 is a wasteful number, since it uses less digits than its factorization.

21104521205205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15628605.

The product of its (nonzero) digits is 8000, while the sum is 30.

Adding to 21104521205205 its reverse (50250212540112), we get a palindrome (71354733745317).

The spelling of 21104521205205 in words is "twenty-one trillion, one hundred four billion, five hundred twenty-one million, two hundred five thousand, two hundred five".