1211111221111 has 4 divisors (see below), whose sum is σ = 1321212241224. Its totient is φ = 1101010201000.

The previous prime is 1211111221051. The next prime is 1211111221171. The reversal of 1211111221111 is 1111221111121.

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

It is an interprime number because it is at equal distance from previous prime (1211111221051) and next prime (1211111221171).

It is a cyclic number.

It is not a de Polignac number, because 1211111221111 - 2³⁵ = 1176751482743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211111221171) 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, 55050510040 + ... + 55050510061.

It is an arithmetic number, because the mean of its divisors is an integer number (330303060306).

Almost surely, 2^{1211111221111} is an apocalyptic number.

1211111221111 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1211111221111 is a deficient number, since it is larger than the sum of its proper divisors (110101020113).

1211111221111 is a wasteful number, since it uses less digits than its factorization.

1211111221111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110101020112.

The product of its digits is 8, while the sum is 16.

Adding to 1211111221111 its reverse (1111221111121), we get a palindrome (2322332332232).

It can be divided in two parts, 121 and 1111221111, that multiplied together give a palindrome (134457754431).

The spelling of 1211111221111 in words is "one trillion, two hundred eleven billion, one hundred eleven million, two hundred twenty-one thousand, one hundred eleven".