1111211121221 has 2 divisors, whose sum is σ = 1111211121222. Its totient is φ = 1111211121220.

The previous prime is 1111211121121. The next prime is 1111211121277. The reversal of 1111211121221 is 1221211121111.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 729126424321 + 382084696900 = 853889^2 + 618130^2 .

It is an emirp because it is prime and its reverse (1221211121111) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1111211121221 - 2¹⁴ = 1111211104837 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1111211121221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1111211121121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 555605560610 + 555605560611.

It is an arithmetic number, because the mean of its divisors is an integer number (555605560611).

Almost surely, 2^{1111211121221} is an apocalyptic number.

It is an amenable number.

1111211121221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1111211121221 is an equidigital number, since it uses as much as digits as its factorization.

1111211121221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16, while the sum is 17.

Adding to 1111211121221 its reverse (1221211121111), we get a palindrome (2332422242332).

The spelling of 1111211121221 in words is "one trillion, one hundred eleven billion, two hundred eleven million, one hundred twenty-one thousand, two hundred twenty-one".