643684518 has 12 divisors (see below), whose sum is σ = 1394649828. Its totient is φ = 214561500.

The previous prime is 643684507. The next prime is 643684553. The reversal of 643684518 is 815486346.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17880108 + ... + 17880143.

It is an arithmetic number, because the mean of its divisors is an integer number (116220819).

Almost surely, 2^643684518 is an apocalyptic number.

643684518 is an abundant number, since it is smaller than the sum of its proper divisors (750965310).

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

643684518 is a wasteful number, since it uses less digits than its factorization.

643684518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35760259 (or 35760256 counting only the distinct ones).

The product of its digits is 552960, while the sum is 45.

The square root of 643684518 is about 25370.9384532776. The cubic root of 643684518 is about 863.4244736480.

It can be divided in two parts, 64368 and 4518, that added together give a palindrome (68886).

The spelling of 643684518 in words is "six hundred forty-three million, six hundred eighty-four thousand, five hundred eighteen".