643645660 has 48 divisors (see below), whose sum is σ = 1559222784. Its totient is φ = 218611008.

The previous prime is 643645657. The next prime is 643645669. The reversal of 643645660 is 66546346.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643645669) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6504 + ... + 36463.

It is an arithmetic number, because the mean of its divisors is an integer number (32483808).

Almost surely, 2^643645660 is an apocalyptic number.

It is an amenable number.

643645660 is an abundant number, since it is smaller than the sum of its proper divisors (915577124).

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

643645660 is a wasteful number, since it uses less digits than its factorization.

643645660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43090 (or 43088 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 40.

The square root of 643645660 is about 25370.1726442687. The cubic root of 643645660 is about 863.4070988718.

The spelling of 643645660 in words is "six hundred forty-three million, six hundred forty-five thousand, six hundred sixty".