647978 has 8 divisors (see below), whose sum is σ = 990468. Its totient is φ = 317824.

The previous prime is 647963. The next prime is 647987. The reversal of 647978 is 879746.

647978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 635209 + 12769 = 797^2 + 113^2 .

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

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 647978.

It is an unprimeable number.

647978 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2951 + ... + 3162.

2⁶⁴⁷⁹⁷⁸ is an apocalyptic number.

647978 is a deficient number, since it is larger than the sum of its proper divisors (342490).

647978 is a wasteful number, since it uses less digits than its factorization.

647978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6168.

The product of its digits is 84672, while the sum is 41.

The square root of 647978 is about 804.9708069241. The cubic root of 647978 is about 86.5339949021.

The spelling of 647978 in words is "six hundred forty-seven thousand, nine hundred seventy-eight".