21221204121211 has 16 divisors (see below), whose sum is σ = 21629741877760. Its totient is φ = 20814653566080.

The previous prime is 21221204121203. The next prime is 21221204121233. The reversal of 21221204121211 is 11212140212212.

It is a cyclic number.

It is not a de Polignac number, because 21221204121211 - 2³ = 21221204121203 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21221204121251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 83882470 + ... + 84135076.

It is an arithmetic number, because the mean of its divisors is an integer number (1351858867360).

Almost surely, 2^{21221204121211} is an apocalyptic number.

21221204121211 is a deficient number, since it is larger than the sum of its proper divisors (408537756549).

21221204121211 is a wasteful number, since it uses less digits than its factorization.

21221204121211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 256534.

The product of its (nonzero) digits is 256, while the sum is 22.

Adding to 21221204121211 its reverse (11212140212212), we get a palindrome (32433344333423).

The spelling of 21221204121211 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred four million, one hundred twenty-one thousand, two hundred eleven".