21165201066105 has 24 divisors (see below), whose sum is σ = 36687043690440. Its totient is φ = 11287893335040.

The previous prime is 21165201066071. The next prime is 21165201066151. The reversal of 21165201066105 is 50166010256112.

21165201066105 is a `hidden beast` number, since 2 + 1 + 1 + 6 + 5 + 20 + 10 + 6 + 610 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 722396303721 + 20442804762384 = 849939^2 + 4521372^2 .

It is not a de Polignac number, because 21165201066105 - 2¹¹ = 21165201064057 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21165201066105.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2040706 + ... + 6818715.

It is an arithmetic number, because the mean of its divisors is an integer number (1528626820435).

Almost surely, 2^{21165201066105} is an apocalyptic number.

It is an amenable number.

21165201066105 is a deficient number, since it is larger than the sum of its proper divisors (15521842624335).

21165201066105 is a wasteful number, since it uses less digits than its factorization.

21165201066105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8912521 (or 8912518 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The spelling of 21165201066105 in words is "twenty-one trillion, one hundred sixty-five billion, two hundred one million, sixty-six thousand, one hundred five".