221221112122121 has 4 divisors (see below), whose sum is σ = 221618277494532. Its totient is φ = 220823946749712.

The previous prime is 221221112122097. The next prime is 221221112122133. The reversal of 221221112122121 is 121221211122122.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 141061680009721 + 80159432112400 = 11876939^2 + 8953180^2 .

It is a cyclic number.

It is not a de Polignac number, because 221221112122121 - 2¹⁴ = 221221112105737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221221112122141) 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, 198582685370 + ... + 198582686483.

It is an arithmetic number, because the mean of its divisors is an integer number (55404569373633).

Almost surely, 2^{221221112122121} is an apocalyptic number.

It is an amenable number.

221221112122121 is a deficient number, since it is larger than the sum of its proper divisors (397165372411).

221221112122121 is an equidigital number, since it uses as much as digits as its factorization.

221221112122121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397165372410.

The product of its digits is 256, while the sum is 23.

Adding to 221221112122121 its reverse (121221211122122), we get a palindrome (342442323244243).

Subtracting from 221221112122121 its reverse (121221211122122), we obtain a palindrome (99999900999999).

The spelling of 221221112122121 in words is "two hundred twenty-one trillion, two hundred twenty-one billion, one hundred twelve million, one hundred twenty-two thousand, one hundred twenty-one".