278991 has 8 divisors (see below), whose sum is σ = 413360. Its totient is φ = 185976.

The previous prime is 278981. The next prime is 279001. The reversal of 278991 is 199872.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (278981) and next prime (279001).

It is not a de Polignac number, because 278991 - 2⁹ = 278479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 278991.

It is not an unprimeable number, because it can be changed into a prime (278911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5140 + ... + 5193.

It is an arithmetic number, because the mean of its divisors is an integer number (51670).

2²⁷⁸⁹⁹¹ is an apocalyptic number.

278991 is a deficient number, since it is larger than the sum of its proper divisors (134369).

278991 is a wasteful number, since it uses less digits than its factorization.

278991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10342 (or 10336 counting only the distinct ones).

The product of its digits is 9072, while the sum is 36.

The square root of 278991 is about 528.1959863536. The cubic root of 278991 is about 65.3426481466.

The spelling of 278991 in words is "two hundred seventy-eight thousand, nine hundred ninety-one".