665525565 has 20 divisors (see below), whose sum is σ = 1193016924. Its totient is φ = 354946752.

The previous prime is 665525519. The next prime is 665525569. The reversal of 665525565 is 565525566.

665525565 is a `hidden beast` number, since 6 + 65 + 5 + 25 + 565 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 483032484 + 182493081 = 21978^2 + 13509^2 .

It is not a de Polignac number, because 665525565 - 2⁶ = 665525501 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 665525565.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665525569) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 821232 + ... + 822041.

Almost surely, 2^665525565 is an apocalyptic number.

It is an amenable number.

665525565 is a deficient number, since it is larger than the sum of its proper divisors (527491359).

665525565 is a wasteful number, since it uses less digits than its factorization.

665525565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1643290 (or 1643281 counting only the distinct ones).

The product of its digits is 1350000, while the sum is 45.

The square root of 665525565 is about 25797.7821721170. The cubic root of 665525565 is about 873.0817580283.

Subtracting from 665525565 its reverse (565525566), we obtain a palindrome (99999999).

The spelling of 665525565 in words is "six hundred sixty-five million, five hundred twenty-five thousand, five hundred sixty-five".