21221112221021 has 8 divisors (see below), whose sum is σ = 21237936439800. Its totient is φ = 21204288564480.

The previous prime is 21221112220993. The next prime is 21221112221033. The reversal of 21221112221021 is 12012221112212.

It can be written as a sum of positive squares in 4 ways, for example, as 1031016852100 + 20190095368921 = 1015390^2 + 4493339^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21221112221021 - 2³⁰ = 21220038479197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221112220984 and 21221112221002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221112221041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 108334115 + ... + 108529823.

It is an arithmetic number, because the mean of its divisors is an integer number (2654742054975).

Almost surely, 2^{21221112221021} is an apocalyptic number.

It is an amenable number.

21221112221021 is a deficient number, since it is larger than the sum of its proper divisors (16824218779).

21221112221021 is a wasteful number, since it uses less digits than its factorization.

21221112221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281119.

The product of its (nonzero) digits is 128, while the sum is 20.

Adding to 21221112221021 its reverse (12012221112212), we get a palindrome (33233333333233).

The spelling of 21221112221021 in words is "twenty-one trillion, two hundred twenty-one billion, one hundred twelve million, two hundred twenty-one thousand, twenty-one".