278328561 has 8 divisors (see below), whose sum is σ = 424119744. Its totient is φ = 159044880.

The previous prime is 278328529. The next prime is 278328563. The reversal of 278328561 is 165823872.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 278328561 - 2⁵ = 278328529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (278328563) 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, 6626850 + ... + 6626891.

It is an arithmetic number, because the mean of its divisors is an integer number (53014968).

Almost surely, 2^278328561 is an apocalyptic number.

278328561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

278328561 is a deficient number, since it is larger than the sum of its proper divisors (145791183).

278328561 is a wasteful number, since it uses less digits than its factorization.

278328561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13253751.

The product of its digits is 161280, while the sum is 42.

The square root of 278328561 is about 16683.1819806654. The cubic root of 278328561 is about 652.9089041617.

The spelling of 278328561 in words is "two hundred seventy-eight million, three hundred twenty-eight thousand, five hundred sixty-one".