278491 has 2 divisors, whose sum is σ = 278492. Its totient is φ = 278490.

The previous prime is 278489. The next prime is 278497. The reversal of 278491 is 194872.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 278491 - 2¹ = 278489 is a prime.

Together with 278489, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (278497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139245 + 139246.

It is an arithmetic number, because the mean of its divisors is an integer number (139246).

2²⁷⁸⁴⁹¹ is an apocalyptic number.

278491 is a deficient number, since it is larger than the sum of its proper divisors (1).

278491 is an equidigital number, since it uses as much as digits as its factorization.

278491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4032, while the sum is 31.

The square root of 278491 is about 527.7224649378. The cubic root of 278491 is about 65.3035897050.

The spelling of 278491 in words is "two hundred seventy-eight thousand, four hundred ninety-one".