212121121 has 4 divisors (see below), whose sum is σ = 224598852. Its totient is φ = 199643392.

The previous prime is 212121113. The next prime is 212121139. The reversal of 212121121 is 121121212.

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 166410000 + 45711121 = 12900^2 + 6761^2 .

It is a cyclic number.

It is not a de Polignac number, because 212121121 - 2³ = 212121113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (212121181) 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, 6238840 + ... + 6238873.

It is an arithmetic number, because the mean of its divisors is an integer number (56149713).

Almost surely, 2^212121121 is an apocalyptic number.

It is an amenable number.

212121121 is a deficient number, since it is larger than the sum of its proper divisors (12477731).

212121121 is a wasteful number, since it uses less digits than its factorization.

212121121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12477730.

The product of its digits is 16, while the sum is 13.

The square root of 212121121 is about 14564.3784968669. The cubic root of 212121121 is about 596.3867295105.

Adding to 212121121 its reverse (121121212), we get a palindrome (333242333).

Subtracting from 212121121 its reverse (121121212), we obtain a palindrome (90999909).

It can be divided in two parts, 212 and 121121, that multiplied together give a palindrome (25677652).

The spelling of 212121121 in words is "two hundred twelve million, one hundred twenty-one thousand, one hundred twenty-one".