1211221111181 has 2 divisors, whose sum is σ = 1211221111182. Its totient is φ = 1211221111180.

The previous prime is 1211221111171. The next prime is 1211221111187. The reversal of 1211221111181 is 1811111221121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 637816265956 + 573404845225 = 798634^2 + 757235^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211221111181 - 2⁶ = 1211221111117 is a prime.

It is a super-2 number, since 2×1211221111181² (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 (1211221111187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605610555590 + 605610555591.

It is an arithmetic number, because the mean of its divisors is an integer number (605610555591).

Almost surely, 2^{1211221111181} is an apocalyptic number.

It is an amenable number.

1211221111181 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211221111181 is an equidigital number, since it uses as much as digits as its factorization.

1211221111181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64, while the sum is 23.

The spelling of 1211221111181 in words is "one trillion, two hundred eleven billion, two hundred twenty-one million, one hundred eleven thousand, one hundred eighty-one".