278606891 has 2 divisors, whose sum is σ = 278606892. Its totient is φ = 278606890.

The previous prime is 278606879. The next prime is 278606893. The reversal of 278606891 is 198606872.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-278606891 is a prime.

Together with 278606893, 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 (278606893) 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, 139303445 + 139303446.

It is an arithmetic number, because the mean of its divisors is an integer number (139303446).

Almost surely, 2^278606891 is an apocalyptic number.

278606891 is a deficient number, since it is larger than the sum of its proper divisors (1).

278606891 is an equidigital number, since it uses as much as digits as its factorization.

278606891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 290304, while the sum is 47.

The square root of 278606891 is about 16691.5215304058. The cubic root of 278606891 is about 653.1264690824.

The spelling of 278606891 in words is "two hundred seventy-eight million, six hundred six thousand, eight hundred ninety-one".