21022212101221 has 4 divisors (see below), whose sum is σ = 21022221352972. Its totient is φ = 21022202849472.

The previous prime is 21022212101203. The next prime is 21022212101257. The reversal of 21022212101221 is 12210121222012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 10012351492900 + 11009860608321 = 3164230^2 + 3318111^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21022212101221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022212101291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1392535 + ... + 6632011.

It is an arithmetic number, because the mean of its divisors is an integer number (5255555338243).

Almost surely, 2^{21022212101221} is an apocalyptic number.

It is an amenable number.

21022212101221 is a deficient number, since it is larger than the sum of its proper divisors (9251751).

21022212101221 is an equidigital number, since it uses as much as digits as its factorization.

21022212101221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9251750.

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 21022212101221 its reverse (12210121222012), we get a palindrome (33232333323233).

The spelling of 21022212101221 in words is "twenty-one trillion, twenty-two billion, two hundred twelve million, one hundred one thousand, two hundred twenty-one".