1221112212121 has 4 divisors (see below), whose sum is σ = 1238310975744. Its totient is φ = 1203913448500.

The previous prime is 1221112212119. The next prime is 1221112212191. The reversal of 1221112212121 is 1212122111221.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1221112212121 - 2¹ = 1221112212119 is a prime.

It is a super-2 number, since 2×1221112212121² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221112212101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8599381705 + ... + 8599381846.

It is an arithmetic number, because the mean of its divisors is an integer number (309577743936).

Almost surely, 2^{1221112212121} is an apocalyptic number.

It is an amenable number.

1221112212121 is a deficient number, since it is larger than the sum of its proper divisors (17198763623).

1221112212121 is an equidigital number, since it uses as much as digits as its factorization.

1221112212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17198763622.

The product of its digits is 64, while the sum is 19.

Adding to 1221112212121 its reverse (1212122111221), we get a palindrome (2433234323342).

The spelling of 1221112212121 in words is "one trillion, two hundred twenty-one billion, one hundred twelve million, two hundred twelve thousand, one hundred twenty-one".