643506 has 8 divisors (see below), whose sum is σ = 1287024. Its totient is φ = 214500.

The previous prime is 643493. The next prime is 643507. The reversal of 643506 is 605346.

643506 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

643506 is an admirable number.

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 3 ways as a sum of consecutive naturals, for example, 53620 + ... + 53631.

It is an arithmetic number, because the mean of its divisors is an integer number (160878).

2⁶⁴³⁵⁰⁶ is an apocalyptic number.

643506 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

643506 is a wasteful number, since it uses less digits than its factorization.

643506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107256.

The product of its (nonzero) digits is 2160, while the sum is 24.

The square root of 643506 is about 802.1882572065. The cubic root of 643506 is about 86.3344646208.

It can be divided in two parts, 64 and 3506, that added together give a triangular number (3570 = T₈₄).

The spelling of 643506 in words is "six hundred forty-three thousand, five hundred six".