111212222021 has 4 divisors (see below), whose sum is σ = 117754117452. Its totient is φ = 104670326592.

The previous prime is 111212221997. The next prime is 111212222053. The reversal of 111212222021 is 120222212111.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 120222212111 = 239383 ⋅502217.

It can be written as a sum of positive squares in 2 ways, for example, as 67334541121 + 43877680900 = 259489^2 + 209470^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-111212222021 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 6541895413 = 111212222021 / (1 + 1 + 1 + 2 + 1 + 2 + 2 + 2 + 2 + 0 + 2 + 1).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (111212222521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3270947690 + ... + 3270947723.

It is an arithmetic number, because the mean of its divisors is an integer number (29438529363).

Almost surely, 2^111212222021 is an apocalyptic number.

It is an amenable number.

111212222021 is a deficient number, since it is larger than the sum of its proper divisors (6541895431).

111212222021 is an equidigital number, since it uses as much as digits as its factorization.

111212222021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6541895430.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 111212222021 its reverse (120222212111), we get a palindrome (231434434132).

The spelling of 111212222021 in words is "one hundred eleven billion, two hundred twelve million, two hundred twenty-two thousand, twenty-one".