2121111212221 has 2 divisors, whose sum is σ = 2121111212222. Its totient is φ = 2121111212220.

The previous prime is 2121111212093. The next prime is 2121111212239. The reversal of 2121111212221 is 1222121111212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2108272056121 + 12839156100 = 1451989^2 + 113310^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121111212221 - 2⁷ = 2121111212093 is a prime.

It is a super-2 number, since 2×2121111212221² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2121111212021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060555606110 + 1060555606111.

It is an arithmetic number, because the mean of its divisors is an integer number (1060555606111).

Almost surely, 2^{2121111212221} is an apocalyptic number.

It is an amenable number.

2121111212221 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121111212221 is an equidigital number, since it uses as much as digits as its factorization.

2121111212221 is an evil number, because the sum of its binary digits is even.

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

Adding to 2121111212221 its reverse (1222121111212), we get a palindrome (3343232323433).

It can be divided in two parts, 2121111 and 212221, that added together give a palindrome (2333332).

The spelling of 2121111212221 in words is "two trillion, one hundred twenty-one billion, one hundred eleven million, two hundred twelve thousand, two hundred twenty-one".