21211021122121 has 4 divisors (see below), whose sum is σ = 21215845102212. Its totient is φ = 21206197142032.

The previous prime is 21211021122089. The next prime is 21211021122167. The reversal of 21211021122121 is 12122112011212.

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 16217856579600 + 4993164542521 = 4027140^2 + 2234539^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211021122121 - 2⁵ = 21211021122089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21211021122721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2411983450 + ... + 2411992243.

It is an arithmetic number, because the mean of its divisors is an integer number (5303961275553).

Almost surely, 2^{21211021122121} is an apocalyptic number.

It is an amenable number.

21211021122121 is a deficient number, since it is larger than the sum of its proper divisors (4823980091).

21211021122121 is an equidigital number, since it uses as much as digits as its factorization.

21211021122121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4823980090.

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

Adding to 21211021122121 its reverse (12122112011212), we get a palindrome (33333133133333).

The spelling of 21211021122121 in words is "twenty-one trillion, two hundred eleven billion, twenty-one million, one hundred twenty-two thousand, one hundred twenty-one".