21100213109 has 2 divisors, whose sum is σ = 21100213110. Its totient is φ = 21100213108.

The previous prime is 21100213093. The next prime is 21100213139. The reversal of 21100213109 is 90131200112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10592938084 + 10507275025 = 102922^2 + 102505^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100213109 - 2⁴ = 21100213093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100213139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550106554 + 10550106555.

It is an arithmetic number, because the mean of its divisors is an integer number (10550106555).

Almost surely, 2^21100213109 is an apocalyptic number.

It is an amenable number.

21100213109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100213109 is an equidigital number, since it uses as much as digits as its factorization.

21100213109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 108, while the sum is 20.

The spelling of 21100213109 in words is "twenty-one billion, one hundred million, two hundred thirteen thousand, one hundred nine".