278605 has 4 divisors (see below), whose sum is σ = 334332. Its totient is φ = 222880.

The previous prime is 278591. The next prime is 278609. The reversal of 278605 is 506872.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 218089 + 60516 = 467^2 + 246^2 .

It is not a de Polignac number, because 278605 - 2¹¹ = 276557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (278609) 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, 27856 + ... + 27865.

It is an arithmetic number, because the mean of its divisors is an integer number (83583).

2²⁷⁸⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

278605 is a deficient number, since it is larger than the sum of its proper divisors (55727).

278605 is an equidigital number, since it uses as much as digits as its factorization.

278605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55726.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 278605 is about 527.8304652064. The cubic root of 278605 is about 65.3124991415.

The spelling of 278605 in words is "two hundred seventy-eight thousand, six hundred five".