2121021220121 has 4 divisors (see below), whose sum is σ = 2172753445044. Its totient is φ = 2069288995200.

The previous prime is 2121021220093. The next prime is 2121021220133. The reversal of 2121021220121 is 1210221201212.

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 388733545225 + 1732287674896 = 623485^2 + 1316164^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121021220121 - 2²⁶ = 2120954111257 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2121021220121.

It is not an unprimeable number, because it can be changed into a prime (2121021229121) 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, 25866112400 + ... + 25866112481.

It is an arithmetic number, because the mean of its divisors is an integer number (543188361261).

Almost surely, 2^{2121021220121} is an apocalyptic number.

It is an amenable number.

2121021220121 is a deficient number, since it is larger than the sum of its proper divisors (51732224923).

2121021220121 is an equidigital number, since it uses as much as digits as its factorization.

2121021220121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51732224922.

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

Adding to 2121021220121 its reverse (1210221201212), we get a palindrome (3331242421333).

The spelling of 2121021220121 in words is "two trillion, one hundred twenty-one billion, twenty-one million, two hundred twenty thousand, one hundred twenty-one".