221220121121 has 4 divisors (see below), whose sum is σ = 221229362244. Its totient is φ = 221210880000.

The previous prime is 221220121061. The next prime is 221220121127. The reversal of 221220121121 is 121121022122.

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 147505156096 + 73714965025 = 384064^2 + 271505^2 .

It is a cyclic number.

It is not a de Polignac number, because 221220121121 - 2¹⁴ = 221220104737 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 221220121121.

It is not an unprimeable number, because it can be changed into a prime (221220121127) 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, 4584560 + ... + 4632561.

It is an arithmetic number, because the mean of its divisors is an integer number (55307340561).

Almost surely, 2^221220121121 is an apocalyptic number.

It is an amenable number.

221220121121 is a deficient number, since it is larger than the sum of its proper divisors (9241123).

221220121121 is an equidigital number, since it uses as much as digits as its factorization.

221220121121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9241122.

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

Adding to 221220121121 its reverse (121121022122), we get a palindrome (342341143243).

It can be divided in two parts, 2212201 and 21121, that added together give a palindrome (2233322).

The spelling of 221220121121 in words is "two hundred twenty-one billion, two hundred twenty million, one hundred twenty-one thousand, one hundred twenty-one".