111211211211221 has 6 divisors (see below), whose sum is σ = 122240422240566. Its totient is φ = 101101101101000.

The previous prime is 111211211211197. The next prime is 111211211211223. The reversal of 111211211211221 is 122112112112111.

It can be written as a sum of positive squares in only one way, i.e., 95155050015025 + 16056161196196 = 9754745^2 + 4007014^2 .

It is not a de Polignac number, because 111211211211221 - 2³⁰ = 111210137469397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 111211211211193 and 111211211211202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111211211211223) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 459550459430 + ... + 459550459671.

It is an arithmetic number, because the mean of its divisors is an integer number (20373403706761).

Almost surely, 2^{111211211211221} is an apocalyptic number.

111211211211221 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

111211211211221 is a deficient number, since it is larger than the sum of its proper divisors (11029211029345).

111211211211221 is an equidigital number, since it uses as much as digits as its factorization.

111211211211221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 919100919123 (or 919100919112 counting only the distinct ones).

The product of its digits is 32, while the sum is 20.

Adding to 111211211211221 its reverse (122112112112111), we get a palindrome (233323323323332).

The spelling of 111211211211221 in words is "one hundred eleven trillion, two hundred eleven billion, two hundred eleven million, two hundred eleven thousand, two hundred twenty-one".