643760 has 40 divisors (see below), whose sum is σ = 1614480. Its totient is φ = 237312.

The previous prime is 643751. The next prime is 643781. The reversal of 643760 is 67346.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (26).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 731 + ... + 1349.

It is an arithmetic number, because the mean of its divisors is an integer number (40362).

2⁶⁴³⁷⁶⁰ 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 643760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (807240).

643760 is an abundant number, since it is smaller than the sum of its proper divisors (970720).

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

643760 is a wasteful number, since it uses less digits than its factorization.

643760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 645 (or 639 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 26.

The square root of 643760 is about 802.3465585394. The cubic root of 643760 is about 86.3458222302.

The spelling of 643760 in words is "six hundred forty-three thousand, seven hundred sixty".