665278 has 12 divisors (see below), whose sum is σ = 1060992. Its totient is φ = 312800.

The previous prime is 665267. The next prime is 665279. The reversal of 665278 is 872566.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665279) by changing a digit.

665278 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3 + ... + 1153.

It is an arithmetic number, because the mean of its divisors is an integer number (88416).

2⁶⁶⁵²⁷⁸ is an apocalyptic number.

665278 is a deficient number, since it is larger than the sum of its proper divisors (395714).

665278 is a wasteful number, since it uses less digits than its factorization.

665278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1187 (or 1170 counting only the distinct ones).

The product of its digits is 20160, while the sum is 34.

The square root of 665278 is about 815.6457564409. The cubic root of 665278 is about 87.2973487060.

The spelling of 665278 in words is "six hundred sixty-five thousand, two hundred seventy-eight".