1211221111111 has 4 divisors (see below), whose sum is σ = 1321332121224. Its totient is φ = 1101110101000.

The previous prime is 1211221111109. The next prime is 1211221111117. The reversal of 1211221111111 is 1111111221121.

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

It is a cyclic number.

It is not a de Polignac number, because 1211221111111 - 2¹ = 1211221111109 is a prime.

It is a Duffinian number.

1211221111111 is a modest number, since divided by 1111111 gives 121122 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211221111117) 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, 55055505040 + ... + 55055505061.

It is an arithmetic number, because the mean of its divisors is an integer number (330333030306).

Almost surely, 2^{1211221111111} is an apocalyptic number.

1211221111111 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1211221111111 is a deficient number, since it is larger than the sum of its proper divisors (110111010113).

1211221111111 is a wasteful number, since it uses less digits than its factorization.

1211221111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110111010112.

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

Adding to 1211221111111 its reverse (1111111221121), we get a palindrome (2322332332232).

The spelling of 1211221111111 in words is "one trillion, two hundred eleven billion, two hundred twenty-one million, one hundred eleven thousand, one hundred eleven".