643986560 has 128 divisors (see below), whose sum is σ = 1816611840. Its totient is φ = 213626880.

The previous prime is 643986523. The next prime is 643986613. The reversal of 643986560 is 65689346.

It is a tau number, because it is divible by the number of its divisors (128).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 136562 + ... + 141198.

It is an arithmetic number, because the mean of its divisors is an integer number (14192280).

Almost surely, 2^643986560 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643986560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (908305920).

643986560 is an abundant number, since it is smaller than the sum of its proper divisors (1172625280).

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

643986560 is a wasteful number, since it uses less digits than its factorization.

643986560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4694 (or 4682 counting only the distinct ones).

The product of its (nonzero) digits is 933120, while the sum is 47.

The square root of 643986560 is about 25376.8902744209. The cubic root of 643986560 is about 863.5595033958.

The spelling of 643986560 in words is "six hundred forty-three million, nine hundred eighty-six thousand, five hundred sixty".