6660665 has 16 divisors (see below), whose sum is σ = 8769600. Its totient is φ = 4816320.

The previous prime is 6660649. The next prime is 6660677. The reversal of 6660665 is 5660666.

It is not a de Polignac number, because 6660665 - 2⁴ = 6660649 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18911 + ... + 19259.

It is an arithmetic number, because the mean of its divisors is an integer number (548100).

Almost surely, 2^6660665 is an apocalyptic number.

It is an amenable number.

6660665 is a deficient number, since it is larger than the sum of its proper divisors (2108935).

6660665 is a wasteful number, since it uses less digits than its factorization.

6660665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 712.

The product of its (nonzero) digits is 38880, while the sum is 35.

The square root of 6660665 is about 2580.8264180297. The cubic root of 6660665 is about 188.1507109740.

Subtracting from 6660665 its reverse (5660666), we obtain a palindrome (999999).

The spelling of 6660665 in words is "six million, six hundred sixty thousand, six hundred sixty-five".