665545 has 4 divisors (see below), whose sum is σ = 798660. Its totient is φ = 532432.

The previous prime is 665527. The next prime is 665549. The reversal of 665545 is 545566.

665545 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 356409 + 309136 = 597^2 + 556^2 .

It is a cyclic number.

It is not a de Polignac number, because 665545 - 2¹⁵ = 632777 is a prime.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (665549) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66550 + ... + 66559.

It is an arithmetic number, because the mean of its divisors is an integer number (199665).

2⁶⁶⁵⁵⁴⁵ is an apocalyptic number.

It is an amenable number.

665545 is a deficient number, since it is larger than the sum of its proper divisors (133115).

665545 is a wasteful number, since it uses less digits than its factorization.

665545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133114.

The product of its digits is 18000, while the sum is 31.

The square root of 665545 is about 815.8094140178. The cubic root of 665545 is about 87.3090256664.

The spelling of 665545 in words is "six hundred sixty-five thousand, five hundred forty-five".