278721 has 24 divisors (see below), whose sum is σ = 442624. Its totient is φ = 174960.

The previous prime is 278717. The next prime is 278741. The reversal of 278721 is 127872.

It is not a de Polignac number, because 278721 - 2² = 278717 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 278721.

It is not an unprimeable number, because it can be changed into a prime (278701) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 7515 + ... + 7551.

2²⁷⁸⁷²¹ is an apocalyptic number.

It is an amenable number.

278721 is a deficient number, since it is larger than the sum of its proper divisors (163903).

278721 is an equidigital number, since it uses as much as digits as its factorization.

278721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 71 counting only the distinct ones).

The product of its digits is 1568, while the sum is 27.

The square root of 278721 is about 527.9403375382. The cubic root of 278721 is about 65.3215623895.

It can be divided in two parts, 278 and 721, that added together give a palindrome (999).

The spelling of 278721 in words is "two hundred seventy-eight thousand, seven hundred twenty-one".