278865 has 12 divisors (see below), whose sum is σ = 483444. Its totient is φ = 148704.

The previous prime is 278849. The next prime is 278867. The reversal of 278865 is 568872.

It can be written as a sum of positive squares in 2 ways, for example, as 104976 + 173889 = 324^2 + 417^2 .

It is not a de Polignac number, because 278865 - 2⁴ = 278849 is a prime.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 278865.

It is not an unprimeable number, because it can be changed into a prime (278867) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3054 + ... + 3143.

It is an arithmetic number, because the mean of its divisors is an integer number (40287).

2²⁷⁸⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

278865 is a deficient number, since it is larger than the sum of its proper divisors (204579).

278865 is a wasteful number, since it uses less digits than its factorization.

278865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6208 (or 6205 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 278865 is about 528.0766989747. The cubic root of 278865 is about 65.3328098204.

The spelling of 278865 in words is "two hundred seventy-eight thousand, eight hundred sixty-five".