1278399647 has 8 divisors (see below), whose sum is σ = 1462964256. Its totient is φ = 1094319072.

The previous prime is 1278399611. The next prime is 1278399701. The reversal of 1278399647 is 7469938721.

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

It is not a de Polignac number, because 1278399647 - 2⁸ = 1278399391 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1278399592 and 1278399601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1278399047) 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, 115328 + ... + 125925.

It is an arithmetic number, because the mean of its divisors is an integer number (182870532).

Almost surely, 2^1278399647 is an apocalyptic number.

1278399647 is a deficient number, since it is larger than the sum of its proper divisors (184564609).

1278399647 is an equidigital number, since it uses as much as digits as its factorization.

1278399647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 242017.

The product of its digits is 4572288, while the sum is 56.

The square root of 1278399647 is about 35754.7150317269. The cubic root of 1278399647 is about 1085.3143551750.

The spelling of 1278399647 in words is "one billion, two hundred seventy-eight million, three hundred ninety-nine thousand, six hundred forty-seven".