21664523310109 has 2 divisors, whose sum is σ = 21664523310110. Its totient is φ = 21664523310108.

The previous prime is 21664523310103. The next prime is 21664523310169. The reversal of 21664523310109 is 90101332546612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12718424364100 + 8946098946009 = 3566290^2 + 2991003^2 .

It is a cyclic number.

It is not a de Polignac number, because 21664523310109 - 2⁷ = 21664523309981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21664523310103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10832261655054 + 10832261655055.

It is an arithmetic number, because the mean of its divisors is an integer number (10832261655055).

Almost surely, 2^{21664523310109} is an apocalyptic number.

It is an amenable number.

21664523310109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21664523310109 is an equidigital number, since it uses as much as digits as its factorization.

21664523310109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 233280, while the sum is 43.

The spelling of 21664523310109 in words is "twenty-one trillion, six hundred sixty-four billion, five hundred twenty-three million, three hundred ten thousand, one hundred nine".