665729 has 4 divisors (see below), whose sum is σ = 667584. Its totient is φ = 663876.

The previous prime is 665723. The next prime is 665747. The reversal of 665729 is 927566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 665729 - 2⁴ = 665713 is a prime.

It is a d-powerful number, because it can be written as 6 + 6² + 7² + 5⁵ + 2¹⁷ + 9⁶ .

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665723) 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, 197 + ... + 1170.

It is an arithmetic number, because the mean of its divisors is an integer number (166896).

2⁶⁶⁵⁷²⁹ is an apocalyptic number.

It is an amenable number.

665729 is a deficient number, since it is larger than the sum of its proper divisors (1855).

665729 is a wasteful number, since it uses less digits than its factorization.

665729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1854.

The product of its digits is 22680, while the sum is 35.

The square root of 665729 is about 815.9221776616. The cubic root of 665729 is about 87.3170708928.

The spelling of 665729 in words is "six hundred sixty-five thousand, seven hundred twenty-nine".