665257 has 4 divisors (see below), whose sum is σ = 668800. Its totient is φ = 661716.

The previous prime is 665251. The next prime is 665267. The reversal of 665257 is 752566.

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, and also an emirpimes, since its reverse is a distinct semiprime: 752566 = 2 ⋅376283.

It is a cyclic number.

It is not a de Polignac number, because 665257 - 2¹¹ = 663209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665251) 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, 1473 + ... + 1870.

It is an arithmetic number, because the mean of its divisors is an integer number (167200).

2⁶⁶⁵²⁵⁷ is an apocalyptic number.

It is an amenable number.

665257 is a deficient number, since it is larger than the sum of its proper divisors (3543).

665257 is a wasteful number, since it uses less digits than its factorization.

665257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3542.

The product of its digits is 12600, while the sum is 31.

The square root of 665257 is about 815.6328831037. The cubic root of 665257 is about 87.2964301609.

The spelling of 665257 in words is "six hundred sixty-five thousand, two hundred fifty-seven".