21212012211121 has 8 divisors (see below), whose sum is σ = 21219859652264. Its totient is φ = 21204165225600.

The previous prime is 21212012211083. The next prime is 21212012211191. The reversal of 21212012211121 is 12111221021212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 4035422074896 + 17176590136225 = 2008836^2 + 4144465^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21212012211121 - 2²⁷ = 21211877993393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21212012211191) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 113765671 + ... + 113951971.

It is an arithmetic number, because the mean of its divisors is an integer number (2652482456533).

Almost surely, 2^{21212012211121} is an apocalyptic number.

It is an amenable number.

21212012211121 is a deficient number, since it is larger than the sum of its proper divisors (7847441143).

21212012211121 is a wasteful number, since it uses less digits than its factorization.

21212012211121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227811.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21212012211121 its reverse (12111221021212), we get a palindrome (33323233232333).

The spelling of 21212012211121 in words is "twenty-one trillion, two hundred twelve billion, twelve million, two hundred eleven thousand, one hundred twenty-one".