1211221111 has 2 divisors, whose sum is σ = 1211221112. Its totient is φ = 1211221110.

The previous prime is 1211221097. The next prime is 1211221129. The reversal of 1211221111 is 1111221121.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1211221111 - 2²¹ = 1209123959 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1211221091 and 1211221100.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211221171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605610555 + 605610556.

It is an arithmetic number, because the mean of its divisors is an integer number (605610556).

Almost surely, 2^1211221111 is an apocalyptic number.

1211221111 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211221111 is an equidigital number, since it uses as much as digits as its factorization.

1211221111 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8, while the sum is 13.

The square root of 1211221111 is about 34802.6020722589. The cubic root of 1211221111 is about 1065.9605786773.

Adding to 1211221111 its reverse (1111221121), we get a palindrome (2322442232).

The spelling of 1211221111 in words is "one billion, two hundred eleven million, two hundred twenty-one thousand, one hundred eleven".