21202120122221 has 16 divisors (see below), whose sum is σ = 21761615805120. Its totient is φ = 20649800138880.

The previous prime is 21202120122199. The next prime is 21202120122257. The reversal of 21202120122221 is 12222102120212.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21202120122221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21202120122193 and 21202120122202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202120152221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 112887131 + ... + 113074791.

It is an arithmetic number, because the mean of its divisors is an integer number (1360100987820).

Almost surely, 2^{21202120122221} is an apocalyptic number.

It is an amenable number.

21202120122221 is a deficient number, since it is larger than the sum of its proper divisors (559495682899).

21202120122221 is a wasteful number, since it uses less digits than its factorization.

21202120122221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206764.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21202120122221 its reverse (12222102120212), we get a palindrome (33424222242433).

The spelling of 21202120122221 in words is "twenty-one trillion, two hundred two billion, one hundred twenty million, one hundred twenty-two thousand, two hundred twenty-one".