665731 has 4 divisors (see below), whose sum is σ = 726264. Its totient is φ = 605200.

The previous prime is 665723. The next prime is 665747. The reversal of 665731 is 137566.

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 665731 - 2³ = 665723 is a prime.

It is a super-2 number, since 2×665731² = 886395528722, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 665731.

It is not an unprimeable number, because it can be changed into a prime (665761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30250 + ... + 30271.

It is an arithmetic number, because the mean of its divisors is an integer number (181566).

2⁶⁶⁵⁷³¹ is an apocalyptic number.

665731 is a deficient number, since it is larger than the sum of its proper divisors (60533).

665731 is a wasteful number, since it uses less digits than its factorization.

665731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60532.

The product of its digits is 3780, while the sum is 28.

The square root of 665731 is about 815.9234032677. The cubic root of 665731 is about 87.3171583327.

The spelling of 665731 in words is "six hundred sixty-five thousand, seven hundred thirty-one".