1664855972517 has 16 divisors (see below), whose sum is σ = 2222550392832. Its totient is φ = 1108533040560.

The previous prime is 1664855972513. The next prime is 1664855972561. The reversal of 1664855972517 is 7152795584661.

It is not a de Polignac number, because 1664855972517 - 2² = 1664855972513 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1664855972513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 29474292 + ... + 29530722.

It is an arithmetic number, because the mean of its divisors is an integer number (138909399552).

Almost surely, 2^{1664855972517} is an apocalyptic number.

It is an amenable number.

1664855972517 is a deficient number, since it is larger than the sum of its proper divisors (557694420315).

1664855972517 is a wasteful number, since it uses less digits than its factorization.

1664855972517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68408.

The product of its digits is 127008000, while the sum is 66.

The spelling of 1664855972517 in words is "one trillion, six hundred sixty-four billion, eight hundred fifty-five million, nine hundred seventy-two thousand, five hundred seventeen".