278668399 has 2 divisors, whose sum is σ = 278668400. Its totient is φ = 278668398.

The previous prime is 278668381. The next prime is 278668409. The reversal of 278668399 is 993866872.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 278668399 - 2⁵ = 278668367 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278669399) 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, 139334199 + 139334200.

It is an arithmetic number, because the mean of its divisors is an integer number (139334200).

Almost surely, 2^278668399 is an apocalyptic number.

278668399 is a deficient number, since it is larger than the sum of its proper divisors (1).

278668399 is an equidigital number, since it uses as much as digits as its factorization.

278668399 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7838208, while the sum is 58.

The square root of 278668399 is about 16693.3639210316. The cubic root of 278668399 is about 653.1745290889.

The spelling of 278668399 in words is "two hundred seventy-eight million, six hundred sixty-eight thousand, three hundred ninety-nine".