643768 has 8 divisors (see below), whose sum is σ = 1207080. Its totient is φ = 321880.

The previous prime is 643751. The next prime is 643781. The reversal of 643768 is 867346.

643768 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

643768 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40228 + ... + 40243.

It is an arithmetic number, because the mean of its divisors is an integer number (150885).

2⁶⁴³⁷⁶⁸ is an apocalyptic number.

It is an amenable number.

643768 is a deficient number, since it is larger than the sum of its proper divisors (563312).

643768 is a wasteful number, since it uses less digits than its factorization.

643768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80477 (or 80473 counting only the distinct ones).

The product of its digits is 24192, while the sum is 34.

The square root of 643768 is about 802.3515439008. The cubic root of 643768 is about 86.3461799017.

The spelling of 643768 in words is "six hundred forty-three thousand, seven hundred sixty-eight".