643542644 has 24 divisors (see below), whose sum is σ = 1155517440. Its totient is φ = 313435584.

The previous prime is 643542643. The next prime is 643542689. The reversal of 643542644 is 446245346.

It is a junction number, because it is equal to n+sod(n) for n = 643542598 and 643542607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643542643) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 60992 + ... + 70760.

It is an arithmetic number, because the mean of its divisors is an integer number (48146560).

Almost surely, 2^643542644 is an apocalyptic number.

It is an amenable number.

643542644 is a deficient number, since it is larger than the sum of its proper divisors (511974796).

643542644 is a wasteful number, since it uses less digits than its factorization.

643542644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10199 (or 10197 counting only the distinct ones).

The product of its digits is 276480, while the sum is 38.

The square root of 643542644 is about 25368.1423048673. The cubic root of 643542644 is about 863.3610334164.

The spelling of 643542644 in words is "six hundred forty-three million, five hundred forty-two thousand, six hundred forty-four".