21202121111221 has 8 divisors (see below), whose sum is σ = 21209239646720. Its totient is φ = 21195002924208.

The previous prime is 21202121111177. The next prime is 21202121111239. The reversal of 21202121111221 is 12211112120212.

It is a happy number.

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 21202121111221 - 2³⁵ = 21167761372853 is a prime.

It is a super-2 number, since 2×21202121111221² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202121111021) 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, 187894000 + ... + 188006806.

It is an arithmetic number, because the mean of its divisors is an integer number (2651154955840).

Almost surely, 2^{21202121111221} is an apocalyptic number.

It is an amenable number.

21202121111221 is a deficient number, since it is larger than the sum of its proper divisors (7118535499).

21202121111221 is a wasteful number, since it uses less digits than its factorization.

21202121111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174243.

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

Adding to 21202121111221 its reverse (12211112120212), we get a palindrome (33413233231433).

The spelling of 21202121111221 in words is "twenty-one trillion, two hundred two billion, one hundred twenty-one million, one hundred eleven thousand, two hundred twenty-one".