643858 has 16 divisors (see below), whose sum is σ = 1059480. Its totient is φ = 292096.

The previous prime is 643849. The next prime is 643859. The reversal of 643858 is 858346.

It can be written as a sum of positive squares in 4 ways, for example, as 558009 + 85849 = 747^2 + 293^2 .

It is a Harshad number since it is a multiple of its sum of digits (34).

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (643859) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 660 + ... + 1312.

2⁶⁴³⁸⁵⁸ is an apocalyptic number.

643858 is a deficient number, since it is larger than the sum of its proper divisors (415622).

643858 is a wasteful number, since it uses less digits than its factorization.

643858 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 701.

The product of its digits is 23040, while the sum is 34.

The square root of 643858 is about 802.4076270824. The cubic root of 643858 is about 86.3502035013.

The spelling of 643858 in words is "six hundred forty-three thousand, eight hundred fifty-eight".