278643247 has 4 divisors (see below), whose sum is σ = 281774160. Its totient is φ = 275512336.

The previous prime is 278643241. The next prime is 278643259. The reversal of 278643247 is 742346872.

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

It is a cyclic number.

It is not a de Polignac number, because 278643247 - 2¹⁹ = 278118959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (278643241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1565323 + ... + 1565500.

It is an arithmetic number, because the mean of its divisors is an integer number (70443540).

Almost surely, 2^278643247 is an apocalyptic number.

278643247 is a deficient number, since it is larger than the sum of its proper divisors (3130913).

278643247 is an equidigital number, since it uses as much as digits as its factorization.

278643247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3130912.

The product of its digits is 451584, while the sum is 43.

The square root of 278643247 is about 16692.6105507796. The cubic root of 278643247 is about 653.1548771296.

The spelling of 278643247 in words is "two hundred seventy-eight million, six hundred forty-three thousand, two hundred forty-seven".