2121121212221 has 64 divisors (see below), whose sum is σ = 2514018995712. Its totient is φ = 1768166400000.

The previous prime is 2121121212209. The next prime is 2121121212277. The reversal of 2121121212221 is 1222121211212.

It is not a de Polignac number, because 2121121212221 - 2⁶ = 2121121212157 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2121121212193 and 2121121212202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121121212281) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 886384601 + ... + 886386993.

It is an arithmetic number, because the mean of its divisors is an integer number (39281546808).

Almost surely, 2^{2121121212221} is an apocalyptic number.

It is an amenable number.

2121121212221 is a deficient number, since it is larger than the sum of its proper divisors (392897783491).

2121121212221 is a wasteful number, since it uses less digits than its factorization.

2121121212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3254.

The product of its digits is 128, while the sum is 20.

Adding to 2121121212221 its reverse (1222121211212), we get a palindrome (3343242423433).

The spelling of 2121121212221 in words is "two trillion, one hundred twenty-one billion, one hundred twenty-one million, two hundred twelve thousand, two hundred twenty-one".