21210221120021 has 4 divisors (see below), whose sum is σ = 21894421801344. Its totient is φ = 20526020438700.

The previous prime is 21210221120003. The next prime is 21210221120089. The reversal of 21210221120021 is 12002112201212.

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 21210221120021 - 2³⁸ = 20935343213077 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 (21210221150021) 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, 342100340615 + ... + 342100340676.

It is an arithmetic number, because the mean of its divisors is an integer number (5473605450336).

Almost surely, 2^{21210221120021} is an apocalyptic number.

It is an amenable number.

21210221120021 is a deficient number, since it is larger than the sum of its proper divisors (684200681323).

21210221120021 is an equidigital number, since it uses as much as digits as its factorization.

21210221120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 684200681322.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21210221120021 its reverse (12002112201212), we get a palindrome (33212333321233).

The spelling of 21210221120021 in words is "twenty-one trillion, two hundred ten billion, two hundred twenty-one million, one hundred twenty thousand, twenty-one".