20665711564647 has 16 divisors (see below), whose sum is σ = 27573253829760. Its totient is φ = 13767655754592.

The previous prime is 20665711564621. The next prime is 20665711564669. The reversal of 20665711564647 is 74646511756602.

It is not a de Polignac number, because 20665711564647 - 2⁶ = 20665711564583 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20665711564247) 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, 210248229 + ... + 210346497.

It is an arithmetic number, because the mean of its divisors is an integer number (1723328364360).

Almost surely, 2^{20665711564647} is an apocalyptic number.

20665711564647 is a deficient number, since it is larger than the sum of its proper divisors (6907542265113).

20665711564647 is a wasteful number, since it uses less digits than its factorization.

20665711564647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145822.

The product of its (nonzero) digits is 50803200, while the sum is 60.

The spelling of 20665711564647 in words is "twenty trillion, six hundred sixty-five billion, seven hundred eleven million, five hundred sixty-four thousand, six hundred forty-seven".