278987 has 4 divisors (see below), whose sum is σ = 295416. Its totient is φ = 262560.

The previous prime is 278981. The next prime is 279001. The reversal of 278987 is 789872.

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

It is a cyclic number.

It is not a de Polignac number, because 278987 - 2¹⁸ = 16843 is a prime.

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

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 278987.

It is not an unprimeable number, because it can be changed into a prime (278981) 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, 8189 + ... + 8222.

It is an arithmetic number, because the mean of its divisors is an integer number (73854).

2²⁷⁸⁹⁸⁷ is an apocalyptic number.

278987 is a deficient number, since it is larger than the sum of its proper divisors (16429).

278987 is a wasteful number, since it uses less digits than its factorization.

278987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16428.

The product of its digits is 56448, while the sum is 41.

The square root of 278987 is about 528.1921998667. The cubic root of 278987 is about 65.3423358644.

The spelling of 278987 in words is "two hundred seventy-eight thousand, nine hundred eighty-seven".