643647136 has 24 divisors (see below), whose sum is σ = 1382379264. Its totient is φ = 292566720.

The previous prime is 643647131. The next prime is 643647143. The reversal of 643647136 is 631746346.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (643647131) 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 3 ways as a sum of consecutive naturals, for example, 913920 + ... + 914623.

It is an arithmetic number, because the mean of its divisors is an integer number (57599136).

Almost surely, 2^643647136 is an apocalyptic number.

It is an amenable number.

643647136 is an abundant number, since it is smaller than the sum of its proper divisors (738732128).

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

643647136 is a wasteful number, since it uses less digits than its factorization.

643647136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1828564 (or 1828556 counting only the distinct ones).

The product of its digits is 217728, while the sum is 40.

The square root of 643647136 is about 25370.2017335298. The cubic root of 643647136 is about 863.4077588560.

The spelling of 643647136 in words is "six hundred forty-three million, six hundred forty-seven thousand, one hundred thirty-six".