665615665 has 16 divisors (see below), whose sum is σ = 938379456. Its totient is φ = 446846400.

The previous prime is 665615651. The next prime is 665615669. The reversal of 665615665 is 566516566.

It is not a de Polignac number, because 665615665 - 2⁵ = 665615633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665615669) 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, 464751 + ... + 466180.

It is an arithmetic number, because the mean of its divisors is an integer number (58648716).

Almost surely, 2^665615665 is an apocalyptic number.

665615665 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

665615665 is a deficient number, since it is larger than the sum of its proper divisors (272763791).

665615665 is a wasteful number, since it uses less digits than its factorization.

665615665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 930960.

The product of its digits is 972000, while the sum is 46.

The square root of 665615665 is about 25799.5283871624. The cubic root of 665615665 is about 873.1211560224.

Subtracting from 665615665 its reverse (566516566), we obtain a palindrome (99099099).

The spelling of 665615665 in words is "six hundred sixty-five million, six hundred fifteen thousand, six hundred sixty-five".