6660660665 has 8 divisors (see below), whose sum is σ = 7993272840. Its totient is φ = 5328208512.

The previous prime is 6660660661. The next prime is 6660660703. The reversal of 6660660665 is 5660660666.

It can be written as a sum of positive squares in 4 ways, for example, as 721029904 + 5939630761 = 26852^2 + 77069^2 .

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 6660660665 - 2² = 6660660661 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6660660661) 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, 89957 + ... + 146333.

It is an arithmetic number, because the mean of its divisors is an integer number (999159105).

Almost surely, 2^6660660665 is an apocalyptic number.

It is an amenable number.

6660660665 is a deficient number, since it is larger than the sum of its proper divisors (1332612175).

6660660665 is a wasteful number, since it uses less digits than its factorization.

6660660665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80011.

The product of its (nonzero) digits is 1399680, while the sum is 47.

The square root of 6660660665 is about 81612.8707067703. The cubic root of 6660660665 is about 1881.5067015558.

Subtracting from 6660660665 its reverse (5660660666), we obtain a palindrome (999999999).

The spelling of 6660660665 in words is "six billion, six hundred sixty million, six hundred sixty thousand, six hundred sixty-five".