278315561 has 4 divisors (see below), whose sum is σ = 283566852. Its totient is φ = 273064272.

The previous prime is 278315537. The next prime is 278315563. The reversal of 278315561 is 165513872.

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

It can be written as a sum of positive squares in 2 ways, for example, as 80209936 + 198105625 = 8956^2 + 14075^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-278315561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (278315563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2625566 + ... + 2625671.

It is an arithmetic number, because the mean of its divisors is an integer number (70891713).

Almost surely, 2^278315561 is an apocalyptic number.

It is an amenable number.

278315561 is a deficient number, since it is larger than the sum of its proper divisors (5251291).

278315561 is an equidigital number, since it uses as much as digits as its factorization.

278315561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5251290.

The product of its digits is 50400, while the sum is 38.

The square root of 278315561 is about 16682.7923621916. The cubic root of 278315561 is about 652.8987387804.

The spelling of 278315561 in words is "two hundred seventy-eight million, three hundred fifteen thousand, five hundred sixty-one".