278861 has 8 divisors (see below), whose sum is σ = 308448. Its totient is φ = 250000.

The previous prime is 278849. The next prime is 278867. The reversal of 278861 is 168872.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 6-Lehmer number, since φ(278861) divides (278861-1)⁶.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-278861 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 (278867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 986 + ... + 1236.

It is an arithmetic number, because the mean of its divisors is an integer number (38556).

2²⁷⁸⁸⁶¹ is an apocalyptic number.

It is an amenable number.

278861 is a deficient number, since it is larger than the sum of its proper divisors (29587).

278861 is a wasteful number, since it uses less digits than its factorization.

278861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363.

The product of its digits is 5376, while the sum is 32.

The square root of 278861 is about 528.0729116325. The cubic root of 278861 is about 65.3324974441.

It can be divided in two parts, 27 and 8861, that added together give a palindrome (8888).

The spelling of 278861 in words is "two hundred seventy-eight thousand, eight hundred sixty-one".