21002120202221 has 4 divisors (see below), whose sum is σ = 21004528987200. Its totient is φ = 20999711417244.

The previous prime is 21002120202211. The next prime is 21002120202251. The reversal of 21002120202221 is 12220202120012.

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 21002120202221 - 2¹⁸ = 21002119940077 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 21002120202221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002120202211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1204379411 + ... + 1204396848.

It is an arithmetic number, because the mean of its divisors is an integer number (5251132246800).

Almost surely, 2^{21002120202221} is an apocalyptic number.

It is an amenable number.

21002120202221 is a deficient number, since it is larger than the sum of its proper divisors (2408784979).

21002120202221 is an equidigital number, since it uses as much as digits as its factorization.

21002120202221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2408784978.

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

Adding to 21002120202221 its reverse (12220202120012), we get a palindrome (33222322322233).

The spelling of 21002120202221 in words is "twenty-one trillion, two billion, one hundred twenty million, two hundred two thousand, two hundred twenty-one".