643428 has 36 divisors (see below), whose sum is σ = 1658748. Its totient is φ = 210240.

The previous prime is 643421. The next prime is 643429. The reversal of 643428 is 824346.

It can be written as a sum of positive squares in 2 ways, for example, as 304704 + 338724 = 552^2 + 582^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 643428.

It is not an unprimeable number, because it can be changed into a prime (643421) by changing a digit.

643428 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 in 11 ways as a sum of consecutive naturals, for example, 2050 + ... + 2342.

2⁶⁴³⁴²⁸ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643428, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (829374).

643428 is an abundant number, since it is smaller than the sum of its proper divisors (1015320).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643428 is a wasteful number, since it uses less digits than its factorization.

643428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364 (or 359 counting only the distinct ones).

The product of its digits is 4608, while the sum is 27.

The square root of 643428 is about 802.1396387164. The cubic root of 643428 is about 86.3309762512.

It can be divided in two parts, 6 and 43428, that added together give a palindrome (43434).

The spelling of 643428 in words is "six hundred forty-three thousand, four hundred twenty-eight".