646778618 has 8 divisors (see below), whose sum is σ = 983832480. Its totient is φ = 318834460.

The previous prime is 646778603. The next prime is 646778623. The reversal of 646778618 is 816877646.

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

It is a self number, because there is not a number n which added to its sum of digits gives 646778618.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2277248 + ... + 2277531.

It is an arithmetic number, because the mean of its divisors is an integer number (122979060).

Almost surely, 2^646778618 is an apocalyptic number.

646778618 is a deficient number, since it is larger than the sum of its proper divisors (337053862).

646778618 is a wasteful number, since it uses less digits than its factorization.

646778618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4554852.

The product of its digits is 2709504, while the sum is 53.

The square root of 646778618 is about 25431.8425993871. The cubic root of 646778618 is about 864.8057157742.

The spelling of 646778618 in words is "six hundred forty-six million, seven hundred seventy-eight thousand, six hundred eighteen".