643859 has 2 divisors, whose sum is σ = 643860. Its totient is φ = 643858.

The previous prime is 643849. The next prime is 643873. The reversal of 643859 is 958346.

643859 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643859 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (643849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321929 + 321930.

It is an arithmetic number, because the mean of its divisors is an integer number (321930).

2⁶⁴³⁸⁵⁹ is an apocalyptic number.

643859 is a deficient number, since it is larger than the sum of its proper divisors (1).

643859 is an equidigital number, since it uses as much as digits as its factorization.

643859 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 35.

The square root of 643859 is about 802.4082502068. The cubic root of 643859 is about 86.3502482059.

The spelling of 643859 in words is "six hundred forty-three thousand, eight hundred fifty-nine".