21660506566573 has 16 divisors (see below), whose sum is σ = 25608678641280. Its totient is φ = 17925797889216.

The previous prime is 21660506566571. The next prime is 21660506566597. The reversal of 21660506566573 is 37566560506612.

It is not a de Polignac number, because 21660506566573 - 2¹ = 21660506566571 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21660506566571) 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, 32277190 + ... + 32941432.

It is an arithmetic number, because the mean of its divisors is an integer number (1600542415080).

Almost surely, 2^{21660506566573} is an apocalyptic number.

It is an amenable number.

21660506566573 is a deficient number, since it is larger than the sum of its proper divisors (3948172074707).

21660506566573 is a wasteful number, since it uses less digits than its factorization.

21660506566573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 824916.

The product of its (nonzero) digits is 40824000, while the sum is 58.

The spelling of 21660506566573 in words is "twenty-one trillion, six hundred sixty billion, five hundred six million, five hundred sixty-six thousand, five hundred seventy-three".