665439 has 4 divisors (see below), whose sum is σ = 887256. Its totient is φ = 443624.

The previous prime is 665429. The next prime is 665447. The reversal of 665439 is 934566.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 665439 - 2⁷ = 665311 is a prime.

It is a D-number.

665439 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665419) 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, 110904 + ... + 110909.

It is an arithmetic number, because the mean of its divisors is an integer number (221814).

2⁶⁶⁵⁴³⁹ is an apocalyptic number.

665439 is a deficient number, since it is larger than the sum of its proper divisors (221817).

665439 is a wasteful number, since it uses less digits than its factorization.

665439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221816.

The product of its digits is 19440, while the sum is 33.

The square root of 665439 is about 815.7444452768. The cubic root of 665439 is about 87.3043902433.

The spelling of 665439 in words is "six hundred sixty-five thousand, four hundred thirty-nine".