666171171665 has 8 divisors (see below), whose sum is σ = 799751632680. Its totient is φ = 532706119552.

The previous prime is 666171171661. The next prime is 666171171671. The reversal of 666171171665 is 566171171666.

666171171665 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 80874259456 + 585296912209 = 284384^2 + 765047^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 666171171665 - 2² = 666171171661 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (666171171661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28839524 + ... + 28862613.

It is an arithmetic number, because the mean of its divisors is an integer number (99968954085).

Almost surely, 2^666171171665 is an apocalyptic number.

It is an amenable number.

666171171665 is a deficient number, since it is larger than the sum of its proper divisors (133580461015).

666171171665 is a wasteful number, since it uses less digits than its factorization.

666171171665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57704451.

The product of its digits is 1905120, while the sum is 53.

Subtracting from 666171171665 its reverse (566171171666), we obtain a palindrome (99999999999).

It can be divided in two parts, 6661711 and 71665, that added together give a palindrome (6733376).

The spelling of 666171171665 in words is "six hundred sixty-six billion, one hundred seventy-one million, one hundred seventy-one thousand, six hundred sixty-five".