643511660 has 24 divisors (see below), whose sum is σ = 1474227216. Its totient is φ = 234004160.

The previous prime is 643511633. The next prime is 643511663. The reversal of 643511660 is 66115346.

It is not an unprimeable number, because it can be changed into a prime (643511663) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1462307 + ... + 1462746.

It is an arithmetic number, because the mean of its divisors is an integer number (61426134).

Almost surely, 2^643511660 is an apocalyptic number.

It is an amenable number.

643511660 is an abundant number, since it is smaller than the sum of its proper divisors (830715556).

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

643511660 is a wasteful number, since it uses less digits than its factorization.

643511660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2925073 (or 2925071 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 643511660 is about 25367.5316103085. The cubic root of 643511660 is about 863.3471774024.

The spelling of 643511660 in words is "six hundred forty-three million, five hundred eleven thousand, six hundred sixty".