278664 has 32 divisors (see below), whose sum is σ = 738720. Its totient is φ = 87296.

The previous prime is 278651. The next prime is 278671. The reversal of 278664 is 466872.

278664 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 278664.

It is an unprimeable number.

278664 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67 + ... + 749.

It is an arithmetic number, because the mean of its divisors is an integer number (23085).

278664 is a Friedman number, since it can be written as (76-8)*(4^6+2), using all its digits and the basic arithmetic operations.

2²⁷⁸⁶⁶⁴ is an apocalyptic number.

278664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 278664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (369360).

278664 is an abundant number, since it is smaller than the sum of its proper divisors (460056).

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

278664 is a wasteful number, since it uses less digits than its factorization.

278664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 709 (or 705 counting only the distinct ones).

The product of its digits is 16128, while the sum is 33.

The square root of 278664 is about 527.8863514053. The cubic root of 278664 is about 65.3171092113.

Subtracting from 278664 its sum of digits (33), we obtain a triangular number (278631 = T₇₄₆).

It can be divided in two parts, 2786 and 64, that added together give a triangular number (2850 = T₇₅).

The spelling of 278664 in words is "two hundred seventy-eight thousand, six hundred sixty-four".