21664523310145 has 12 divisors (see below), whose sum is σ = 27437728693140. Its totient is φ = 16419428191584.

The previous prime is 21664523310109. The next prime is 21664523310169. The reversal of 21664523310145 is 54101332546612.

It can be written as a sum of positive squares in 2 ways, for example, as 16545182650929 + 5119340659216 = 4067577^2 + 2262596^2 .

It is not a de Polignac number, because 21664523310145 - 2²¹ = 21664521212993 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6001251190 + ... + 6001254799.

It is an arithmetic number, because the mean of its divisors is an integer number (2286477391095).

Almost surely, 2^{21664523310145} is an apocalyptic number.

It is an amenable number.

21664523310145 is a deficient number, since it is larger than the sum of its proper divisors (5773205382995).

21664523310145 is a wasteful number, since it uses less digits than its factorization.

21664523310145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12002506032 (or 12002506013 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 43.

Adding to 21664523310145 its reverse (54101332546612), we get a palindrome (75765855856757).

The spelling of 21664523310145 in words is "twenty-one trillion, six hundred sixty-four billion, five hundred twenty-three million, three hundred ten thousand, one hundred forty-five".