278864 has 20 divisors (see below), whose sum is σ = 559860. Its totient is φ = 134400.

The previous prime is 278849. The next prime is 278867. The reversal of 278864 is 468872.

It can be written as a sum of positive squares in 2 ways, for example, as 193600 + 85264 = 440^2 + 292^2 .

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 278864.

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

278864 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 (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 164 + ... + 764.

It is an arithmetic number, because the mean of its divisors is an integer number (27993).

2²⁷⁸⁸⁶⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 278864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (279930).

278864 is an abundant number, since it is smaller than the sum of its proper divisors (280996).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

278864 is a wasteful number, since it uses less digits than its factorization.

278864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 638 (or 632 counting only the distinct ones).

The product of its digits is 21504, while the sum is 35.

The square root of 278864 is about 528.0757521417. The cubic root of 278864 is about 65.3327317266.

The spelling of 278864 in words is "two hundred seventy-eight thousand, eight hundred sixty-four".