21100211221021 has 4 divisors (see below), whose sum is σ = 21162823124092. Its totient is φ = 21037599317952.

The previous prime is 21100211221009. The next prime is 21100211221057. The reversal of 21100211221021 is 12012211200112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10858540752900 + 10241670468121 = 3295230^2 + 3200261^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100211221021 - 2⁵ = 21100211220989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21100211220986 and 21100211221004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100211221121) 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, 31305951030 + ... + 31305951703.

It is an arithmetic number, because the mean of its divisors is an integer number (5290705781023).

Almost surely, 2^{21100211221021} is an apocalyptic number.

It is an amenable number.

21100211221021 is a deficient number, since it is larger than the sum of its proper divisors (62611903071).

21100211221021 is an equidigital number, since it uses as much as digits as its factorization.

21100211221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62611903070.

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

Adding to 21100211221021 its reverse (12012211200112), we get a palindrome (33112422421133).

The spelling of 21100211221021 in words is "twenty-one trillion, one hundred billion, two hundred eleven million, two hundred twenty-one thousand, twenty-one".