646783856 has 20 divisors (see below), whose sum is σ = 1283709504. Its totient is φ = 315504000.

The previous prime is 646783849. The next prime is 646783859. The reversal of 646783856 is 658387646.

It is a junction number, because it is equal to n+sod(n) for n = 646783798 and 646783807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646783859) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 492320 + ... + 493631.

Almost surely, 2^646783856 is an apocalyptic number.

It is an amenable number.

646783856 is a deficient number, since it is larger than the sum of its proper divisors (636925648).

646783856 is a wasteful number, since it uses less digits than its factorization.

646783856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 986000 (or 985994 counting only the distinct ones).

The product of its digits is 5806080, while the sum is 53.

The square root of 646783856 is about 25431.9455803130. The cubic root of 646783856 is about 864.8080503392.

The spelling of 646783856 in words is "six hundred forty-six million, seven hundred eighty-three thousand, eight hundred fifty-six".