643828 has 12 divisors (see below), whose sum is σ = 1143072. Its totient is φ = 317240.

The previous prime is 643781. The next prime is 643847. The reversal of 643828 is 828346.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 643828.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 850 + ... + 1417.

It is an arithmetic number, because the mean of its divisors is an integer number (95256).

2⁶⁴³⁸²⁸ is an apocalyptic number.

It is an amenable number.

643828 is a deficient number, since it is larger than the sum of its proper divisors (499244).

643828 is a wasteful number, since it uses less digits than its factorization.

643828 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2342 (or 2340 counting only the distinct ones).

The product of its digits is 9216, while the sum is 31.

The square root of 643828 is about 802.3889331241. The cubic root of 643828 is about 86.3488623431.

It can be divided in two parts, 6 and 43828, that added together give a palindrome (43834).

The spelling of 643828 in words is "six hundred forty-three thousand, eight hundred twenty-eight".