2121222121 has 4 divisors (see below), whose sum is σ = 2170552912. Its totient is φ = 2071891332.

The previous prime is 2121222109. The next prime is 2121222163. The reversal of 2121222121 is 1212221212.

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 2121222121 - 2¹³ = 2121213929 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121222095 and 2121222104.

It is not an unprimeable number, because it can be changed into a prime (2121222721) 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, 24665331 + ... + 24665416.

It is an arithmetic number, because the mean of its divisors is an integer number (542638228).

Almost surely, 2^2121222121 is an apocalyptic number.

It is an amenable number.

2121222121 is a deficient number, since it is larger than the sum of its proper divisors (49330791).

2121222121 is an equidigital number, since it uses as much as digits as its factorization.

2121222121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49330790.

The product of its digits is 64, while the sum is 16.

The square root of 2121222121 is about 46056.7272067827. The cubic root of 2121222121 is about 1284.8784617597.

Adding to 2121222121 its reverse (1212221212), we get a palindrome (3333443333).

Subtracting from 2121222121 its reverse (1212221212), we obtain a palindrome (909000909).

It can be divided in two parts, 2 and 121222121, that multiplied together give a palindrome (242444242).

The spelling of 2121222121 in words is "two billion, one hundred twenty-one million, two hundred twenty-two thousand, one hundred twenty-one".