1221211112111 has 4 divisors (see below), whose sum is σ = 1221546337032. Its totient is φ = 1220875887192.

The previous prime is 1221211112089. The next prime is 1221211112113. The reversal of 1221211112111 is 1112111121221.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221211112111 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1221211112111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221211112113) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 167606996 + ... + 167614281.

It is an arithmetic number, because the mean of its divisors is an integer number (305386584258).

Almost surely, 2^{1221211112111} is an apocalyptic number.

1221211112111 is a deficient number, since it is larger than the sum of its proper divisors (335224921).

1221211112111 is an equidigital number, since it uses as much as digits as its factorization.

1221211112111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 335224920.

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

Adding to 1221211112111 its reverse (1112111121221), we get a palindrome (2333322233332).

The spelling of 1221211112111 in words is "one trillion, two hundred twenty-one billion, two hundred eleven million, one hundred twelve thousand, one hundred eleven".