643928 has 8 divisors (see below), whose sum is σ = 1207380. Its totient is φ = 321960.

The previous prime is 643927. The next prime is 643949. The reversal of 643928 is 829346.

643928 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 d-powerful number, because it can be written as 6 + 4⁵ + 9⁵ + 3¹⁰ + 2¹⁹ + 8³ .

It is a junction number, because it is equal to n+sod(n) for n = 643894 and 643903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40238 + ... + 40253.

2⁶⁴³⁹²⁸ is an apocalyptic number.

It is an amenable number.

643928 is a deficient number, since it is larger than the sum of its proper divisors (563452).

643928 is a wasteful number, since it uses less digits than its factorization.

643928 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80497 (or 80493 counting only the distinct ones).

The product of its digits is 10368, while the sum is 32.

The square root of 643928 is about 802.4512446249. The cubic root of 643928 is about 86.3533327085.

It can be divided in two parts, 6 and 43928, that added together give a palindrome (43934).

The spelling of 643928 in words is "six hundred forty-three thousand, nine hundred twenty-eight".