111121212121 has 4 divisors (see below), whose sum is σ = 112221422244. Its totient is φ = 110021002000.

The previous prime is 111121212101. The next prime is 111121212143. The reversal of 111121212121 is 121212121111.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 121212121111 = 101 ⋅1200120011.

It can be written as a sum of positive squares in 2 ways, for example, as 106382954896 + 4738257225 = 326164^2 + 68835^2 .

It is a cyclic number.

It is not a de Polignac number, because 111121212121 - 2²³ = 111112823513 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 111121212095 and 111121212104.

It is not an unprimeable number, because it can be changed into a prime (111121212101) 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, 550104910 + ... + 550105111.

It is an arithmetic number, because the mean of its divisors is an integer number (28055355561).

Almost surely, 2^111121212121 is an apocalyptic number.

It is an amenable number.

111121212121 is a deficient number, since it is larger than the sum of its proper divisors (1100210123).

111121212121 is a wasteful number, since it uses less digits than its factorization.

111121212121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1100210122.

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

Adding to 111121212121 its reverse (121212121111), we get a palindrome (232333333232).

It can be divided in two parts, 111 and 121212121, that multiplied together give a palindrome (13454545431).

The spelling of 111121212121 in words is "one hundred eleven billion, one hundred twenty-one million, two hundred twelve thousand, one hundred twenty-one".