21220002120221 has 4 divisors (see below), whose sum is σ = 21221317942272. Its totient is φ = 21218686298172.

The previous prime is 21220002120217. The next prime is 21220002120227. The reversal of 21220002120221 is 12202120002212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21220002120221 - 2² = 21220002120217 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21220002120221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220002120227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 657886835 + ... + 657919088.

It is an arithmetic number, because the mean of its divisors is an integer number (5305329485568).

Almost surely, 2^{21220002120221} is an apocalyptic number.

It is an amenable number.

21220002120221 is a deficient number, since it is larger than the sum of its proper divisors (1315822051).

21220002120221 is a wasteful number, since it uses less digits than its factorization.

21220002120221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1315822050.

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21220002120221 its reverse (12202120002212), we get a palindrome (33422122122433).

The spelling of 21220002120221 in words is "twenty-one trillion, two hundred twenty billion, two million, one hundred twenty thousand, two hundred twenty-one".