278961647 has 2 divisors, whose sum is σ = 278961648. Its totient is φ = 278961646.

The previous prime is 278961637. The next prime is 278961649. The reversal of 278961647 is 746169872.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 278961647 - 2²² = 274767343 is a prime.

Together with 278961649, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 278961595 and 278961604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (278961649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139480823 + 139480824.

It is an arithmetic number, because the mean of its divisors is an integer number (139480824).

Almost surely, 2^278961647 is an apocalyptic number.

278961647 is a deficient number, since it is larger than the sum of its proper divisors (1).

278961647 is an equidigital number, since it uses as much as digits as its factorization.

278961647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1016064, while the sum is 50.

The square root of 278961647 is about 16702.1449820076. The cubic root of 278961647 is about 653.4035647174.

Subtracting 278961647 from its reverse (746169872), we obtain a square (467208225 = 21615²).

The spelling of 278961647 in words is "two hundred seventy-eight million, nine hundred sixty-one thousand, six hundred forty-seven".