111111011212121 has 16 divisors (see below), whose sum is σ = 114664549708800. Its totient is φ = 107607418045440.

The previous prime is 111111011212087. The next prime is 111111011212129. The reversal of 111111011212121 is 121212110111111.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 111111011212121 - 2³⁴ = 111093831342937 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 111111011212121.

It is not an unprimeable number, because it can be changed into a prime (111111011212129) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24582176 + ... + 28749006.

It is an arithmetic number, because the mean of its divisors is an integer number (7166534356800).

Almost surely, 2^{111111011212121} is an apocalyptic number.

It is an amenable number.

111111011212121 is a deficient number, since it is larger than the sum of its proper divisors (3553538496679).

111111011212121 is an equidigital number, since it uses as much as digits as its factorization.

111111011212121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4172824.

The product of its (nonzero) digits is 8, while the sum is 17.

Adding to 111111011212121 its reverse (121212110111111), we get a palindrome (232323121323232).

The spelling of 111111011212121 in words is "one hundred eleven trillion, one hundred eleven billion, eleven million, two hundred twelve thousand, one hundred twenty-one".