21112221121021 has 4 divisors (see below), whose sum is σ = 21228863226844. Its totient is φ = 20995579015200.

The previous prime is 21112221120997. The next prime is 21112221121073. The reversal of 21112221121021 is 12012112221112.

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 5217048855396 + 15895172265625 = 2284086^2 + 3986875^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112221121021 - 2⁹ = 21112221120509 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 21112221121021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112221128021) 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, 58321052640 + ... + 58321053001.

It is an arithmetic number, because the mean of its divisors is an integer number (5307215806711).

Almost surely, 2^{21112221121021} is an apocalyptic number.

It is an amenable number.

21112221121021 is a deficient number, since it is larger than the sum of its proper divisors (116642105823).

21112221121021 is a wasteful number, since it uses less digits than its factorization.

21112221121021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116642105822.

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

Adding to 21112221121021 its reverse (12012112221112), we get a palindrome (33124333342133).

The spelling of 21112221121021 in words is "twenty-one trillion, one hundred twelve billion, two hundred twenty-one million, one hundred twenty-one thousand, twenty-one".