1211221212121 has 2 divisors, whose sum is σ = 1211221212122. Its totient is φ = 1211221212120.

The previous prime is 1211221212107. The next prime is 1211221212137. The reversal of 1211221212121 is 1212121221121.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 754500704400 + 456720507721 = 868620^2 + 675811^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211221212121 - 2²¹ = 1211219114969 is a prime.

It is not a weakly prime, because it can be changed into another prime (1211221212151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605610606060 + 605610606061.

It is an arithmetic number, because the mean of its divisors is an integer number (605610606061).

Almost surely, 2^{1211221212121} is an apocalyptic number.

It is an amenable number.

1211221212121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211221212121 is an equidigital number, since it uses as much as digits as its factorization.

1211221212121 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 1211221212121 its reverse (1212121221121), we get a palindrome (2423342433242).

The spelling of 1211221212121 in words is "one trillion, two hundred eleven billion, two hundred twenty-one million, two hundred twelve thousand, one hundred twenty-one".