2121212122221 has 16 divisors (see below), whose sum is σ = 2919745018368. Its totient is φ = 1368417422400.

The previous prime is 2121212122217. The next prime is 2121212122223. The reversal of 2121212122221 is 1222212121212.

It is not a de Polignac number, because 2121212122221 - 2² = 2121212122217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121212122223) 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, 322255 + ... + 2084771.

It is an arithmetic number, because the mean of its divisors is an integer number (182484063648).

Almost surely, 2^{2121212122221} is an apocalyptic number.

It is an amenable number.

2121212122221 is a deficient number, since it is larger than the sum of its proper divisors (798532896147).

2121212122221 is a wasteful number, since it uses less digits than its factorization.

2121212122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1775492.

The product of its digits is 256, while the sum is 21.

Adding to 2121212122221 its reverse (1222212121212), we get a palindrome (3343424243433).

The spelling of 2121212122221 in words is "two trillion, one hundred twenty-one billion, two hundred twelve million, one hundred twenty-two thousand, two hundred twenty-one".