2121121212121 has 4 divisors (see below), whose sum is σ = 2121247931044. Its totient is φ = 2120994493200.

The previous prime is 2121121212103. The next prime is 2121121212137. The reversal of 2121121212121 is 1212121211212.

It is a happy number.

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 1771827210000 + 349294002121 = 1331100^2 + 591011^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2121121212121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2121121212521) 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, 63334350 + ... + 63367831.

It is an arithmetic number, because the mean of its divisors is an integer number (530311982761).

Almost surely, 2^{2121121212121} is an apocalyptic number.

It is an amenable number.

2121121212121 is a deficient number, since it is larger than the sum of its proper divisors (126718923).

2121121212121 is a wasteful number, since it uses less digits than its factorization.

2121121212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126718922.

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

Adding to 2121121212121 its reverse (1212121211212), we get a palindrome (3333242423333).

Subtracting from 2121121212121 its reverse (1212121211212), we obtain a palindrome (909000000909).

The spelling of 2121121212121 in words is "two trillion, one hundred twenty-one billion, one hundred twenty-one million, two hundred twelve thousand, one hundred twenty-one".