643544 has 32 divisors (see below), whose sum is σ = 1347840. Its totient is φ = 285600.

The previous prime is 643523. The next prime is 643547. The reversal of 643544 is 445346.

643544 = 193² + 194² + ... + 208².

643544 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643547) by changing a digit.

643544 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 7 ways as a sum of consecutive naturals, for example, 6197 + ... + 6299.

It is an arithmetic number, because the mean of its divisors is an integer number (42120).

2⁶⁴³⁵⁴⁴ 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 643544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (673920).

643544 is an abundant number, since it is smaller than the sum of its proper divisors (704296).

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

643544 is a wasteful number, since it uses less digits than its factorization.

643544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191 (or 187 counting only the distinct ones).

The product of its digits is 5760, while the sum is 26.

The square root of 643544 is about 802.2119420702. The cubic root of 643544 is about 86.3361639808.

The spelling of 643544 in words is "six hundred forty-three thousand, five hundred forty-four".