21210111002221 has 4 divisors (see below), whose sum is σ = 22132289741472. Its totient is φ = 20287932262972.

The previous prime is 21210111002207. The next prime is 21210111002257. The reversal of 21210111002221 is 12220011101212.

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 21210111002221 - 2²⁹ = 21209574131309 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210111002195 and 21210111002204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210111002621) 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, 461089369591 + ... + 461089369636.

It is an arithmetic number, because the mean of its divisors is an integer number (5533072435368).

Almost surely, 2^{21210111002221} is an apocalyptic number.

It is an amenable number.

21210111002221 is a deficient number, since it is larger than the sum of its proper divisors (922178739251).

21210111002221 is an equidigital number, since it uses as much as digits as its factorization.

21210111002221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 922178739250.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21210111002221 its reverse (12220011101212), we get a palindrome (33430122103433).

The spelling of 21210111002221 in words is "twenty-one trillion, two hundred ten billion, one hundred eleven million, two thousand, two hundred twenty-one".