21602066661605 has 16 divisors (see below), whose sum is σ = 27127050249600. Its totient is φ = 16482912376128.

The previous prime is 21602066661601. The next prime is 21602066661607. The reversal of 21602066661605 is 50616666020612.

It is a cyclic number.

It is not a de Polignac number, because 21602066661605 - 2² = 21602066661601 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21602066661605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21602066661601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 269077427 + ... + 269157696.

It is an arithmetic number, because the mean of its divisors is an integer number (1695440640600).

Almost surely, 2^{21602066661605} is an apocalyptic number.

It is an amenable number.

21602066661605 is a deficient number, since it is larger than the sum of its proper divisors (5524983587995).

21602066661605 is a wasteful number, since it uses less digits than its factorization.

21602066661605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 538235500.

The product of its (nonzero) digits is 933120, while the sum is 47.

The spelling of 21602066661605 in words is "twenty-one trillion, six hundred two billion, sixty-six million, six hundred sixty-one thousand, six hundred five".