12123121221 has 24 divisors (see below), whose sum is σ = 18393588096. Its totient is φ = 7679469600.

The previous prime is 12123121201. The next prime is 12123121289. The reversal of 12123121221 is 12212132121.

It is not a de Polignac number, because 12123121221 - 2¹⁰ = 12123120197 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 12123121194 and 12123121203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12123121201) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 162670 + ... + 225183.

It is an arithmetic number, because the mean of its divisors is an integer number (766399504).

Almost surely, 2^12123121221 is an apocalyptic number.

It is an amenable number.

12123121221 is a deficient number, since it is larger than the sum of its proper divisors (6270466875).

12123121221 is a wasteful number, since it uses less digits than its factorization.

12123121221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 388033 (or 388030 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

Adding to 12123121221 its reverse (12212132121), we get a palindrome (24335253342).

The spelling of 12123121221 in words is "twelve billion, one hundred twenty-three million, one hundred twenty-one thousand, two hundred twenty-one".