12121222221 has 12 divisors (see below), whose sum is σ = 17795456380. Its totient is φ = 7948342080.

The previous prime is 12121222213. The next prime is 12121222279. The reversal of 12121222221 is 12222212121.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 4371060996 + 7750161225 = 66114^2 + 88035^2 .

It is not a de Polignac number, because 12121222221 - 2³ = 12121222213 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 12121222194 and 12121222203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12121292221) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11038816 + ... + 11039913.

Almost surely, 2^12121222221 is an apocalyptic number.

It is an amenable number.

12121222221 is a deficient number, since it is larger than the sum of its proper divisors (5674234159).

12121222221 is a wasteful number, since it uses less digits than its factorization.

12121222221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22078796 (or 22078793 counting only the distinct ones).

The product of its digits is 128, while the sum is 18.

Adding to 12121222221 its reverse (12222212121), we get a palindrome (24343434342).

The spelling of 12121222221 in words is "twelve billion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred twenty-one".