643365864 has 24 divisors (see below), whose sum is σ = 1742449410. Its totient is φ = 214455264.

The previous prime is 643365787. The next prime is 643365881. The reversal of 643365864 is 468563346.

643365864 is a `hidden beast` number, since 64 + 3 + 3 + 6 + 586 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 504361764 + 139004100 = 22458^2 + 11790^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4467747 + ... + 4467890.

Almost surely, 2^643365864 is an apocalyptic number.

It is an amenable number.

643365864 is an abundant number, since it is smaller than the sum of its proper divisors (1099083546).

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

643365864 is a wasteful number, since it uses less digits than its factorization.

643365864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8935649 (or 8935642 counting only the distinct ones).

The product of its digits is 1244160, while the sum is 45.

The square root of 643365864 is about 25364.6577741550. The cubic root of 643365864 is about 863.2819716052.

The spelling of 643365864 in words is "six hundred forty-three million, three hundred sixty-five thousand, eight hundred sixty-four".