643012978 has 16 divisors (see below), whose sum is σ = 1008095616. Its totient is φ = 307026720.

The previous prime is 643012967. The next prime is 643012999. The reversal of 643012978 is 879210346.

643012978 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 643012978.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17950 + ... + 40102.

It is an arithmetic number, because the mean of its divisors is an integer number (63005976).

Almost surely, 2^643012978 is an apocalyptic number.

643012978 is a deficient number, since it is larger than the sum of its proper divisors (365082638).

643012978 is a wasteful number, since it uses less digits than its factorization.

643012978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22809.

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 643012978 is about 25357.7005661002. The cubic root of 643012978 is about 863.1241060971.

The spelling of 643012978 in words is "six hundred forty-three million, twelve thousand, nine hundred seventy-eight".