643500 has 144 divisors (see below), whose sum is σ = 2384928. Its totient is φ = 144000.

The previous prime is 643493. The next prime is 643507. The reversal of 643500 is 5346.

It is a happy number.

643500 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (643493) and next prime (643507).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nialpdrome in base 15.

It is a Saint-Exupery number, since it is equal to the product of the sides of a Pythagorean triangle: 125 × 117 × 44.

It is not an unprimeable number, because it can be changed into a prime (643507) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 49494 + ... + 49506.

It is an arithmetic number, because the mean of its divisors is an integer number (16562).

2⁶⁴³⁵⁰⁰ is an apocalyptic number.

643500 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 643500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1192464).

643500 is an abundant number, since it is smaller than the sum of its proper divisors (1741428).

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

643500 is a wasteful number, since it uses less digits than its factorization.

643500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49 (or 34 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 643500 is about 802.1845174273. The cubic root of 643500 is about 86.3341962947.

Adding to 643500 its reverse (5346), we get a palindrome (648846).

The spelling of 643500 in words is "six hundred forty-three thousand, five hundred".