643264656 has 40 divisors (see below), whose sum is σ = 1663851840. Its totient is φ = 214152576.

The previous prime is 643264651. The next prime is 643264673. The reversal of 643264656 is 656462346.

It is not an unprimeable number, because it can be changed into a prime (643264651) 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 7 ways as a sum of consecutive naturals, for example, 32286 + ... + 48258.

It is an arithmetic number, because the mean of its divisors is an integer number (41596296).

Almost surely, 2^643264656 is an apocalyptic number.

It is an amenable number.

643264656 is an abundant number, since it is smaller than the sum of its proper divisors (1020587184).

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

643264656 is a wasteful number, since it uses less digits than its factorization.

643264656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16823 (or 16817 counting only the distinct ones).

The product of its digits is 622080, while the sum is 42.

The square root of 643264656 is about 25362.6626362454. The cubic root of 643264656 is about 863.2367015505.

The spelling of 643264656 in words is "six hundred forty-three million, two hundred sixty-four thousand, six hundred fifty-six".