666565 has 8 divisors (see below), whose sum is σ = 827640. Its totient is φ = 514752.

The previous prime is 666559. The next prime is 666599. The reversal of 666565 is 565666.

666565 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 3969 + 662596 = 63^2 + 814^2 .

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 666565 - 2³ = 666557 is a prime.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 666565.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2154 + ... + 2443.

It is an arithmetic number, because the mean of its divisors is an integer number (103455).

2⁶⁶⁶⁵⁶⁵ is an apocalyptic number.

It is an amenable number.

666565 is a deficient number, since it is larger than the sum of its proper divisors (161075).

666565 is a wasteful number, since it uses less digits than its factorization.

666565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4631.

The product of its digits is 32400, while the sum is 34.

The square root of 666565 is about 816.4343206897. The cubic root of 666565 is about 87.3536055472.

The spelling of 666565 in words is "six hundred sixty-six thousand, five hundred sixty-five".