21210121222221 has 32 divisors (see below), whose sum is σ = 29199901610880. Its totient is φ = 13688029481984.

The previous prime is 21210121222207. The next prime is 21210121222247. The reversal of 21210121222221 is 12222212101212.

It is a cyclic number.

It is not a de Polignac number, because 21210121222221 - 2²² = 21210117027917 is a prime.

It is a super-2 number, since 2×21210121222221² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210121222201) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5003761 + ... + 8213273.

It is an arithmetic number, because the mean of its divisors is an integer number (912496925340).

Almost surely, 2^{21210121222221} is an apocalyptic number.

It is an amenable number.

21210121222221 is a deficient number, since it is larger than the sum of its proper divisors (7989780388659).

21210121222221 is a wasteful number, since it uses less digits than its factorization.

21210121222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3210125.

The product of its (nonzero) digits is 256, while the sum is 21.

Adding to 21210121222221 its reverse (12222212101212), we get a palindrome (33432333323433).

The spelling of 21210121222221 in words is "twenty-one trillion, two hundred ten billion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred twenty-one".