666320565 has 16 divisors (see below), whose sum is σ = 1076079168. Its totient is φ = 352048896.

The previous prime is 666320521. The next prime is 666320573. The reversal of 666320565 is 565023666.

It is not a de Polignac number, because 666320565 - 2²⁰ = 665271989 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 205972 + ... + 209181.

It is an arithmetic number, because the mean of its divisors is an integer number (67254948).

Almost surely, 2^666320565 is an apocalyptic number.

It is an amenable number.

666320565 is a deficient number, since it is larger than the sum of its proper divisors (409758603).

666320565 is a wasteful number, since it uses less digits than its factorization.

666320565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 415268.

The product of its (nonzero) digits is 194400, while the sum is 39.

The square root of 666320565 is about 25813.1858746649. The cubic root of 666320565 is about 873.4292647406.

The spelling of 666320565 in words is "six hundred sixty-six million, three hundred twenty thousand, five hundred sixty-five".