646560978 has 24 divisors (see below), whose sum is σ = 1504244592. Its totient is φ = 184731624.

The previous prime is 646560961. The next prime is 646560991. The reversal of 646560978 is 879065646.

646560978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 646560978.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1099300 + ... + 1099887.

It is an arithmetic number, because the mean of its divisors is an integer number (62676858).

Almost surely, 2^646560978 is an apocalyptic number.

646560978 is an abundant number, since it is smaller than the sum of its proper divisors (857683614).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646560978 is a wasteful number, since it uses less digits than its factorization.

646560978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2199206 (or 2199199 counting only the distinct ones).

The product of its (nonzero) digits is 2177280, while the sum is 51.

The square root of 646560978 is about 25427.5633516072. The cubic root of 646560978 is about 864.7087029653.

The spelling of 646560978 in words is "six hundred forty-six million, five hundred sixty thousand, nine hundred seventy-eight".