643543 has 4 divisors (see below), whose sum is σ = 647800. Its totient is φ = 639288.

The previous prime is 643523. The next prime is 643547. The reversal of 643543 is 345346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 345346 = 2 ⋅172673.

It is a cyclic number.

It is not a de Polignac number, because 643543 - 2⁹ = 643031 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643547) 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, 1893 + ... + 2206.

It is an arithmetic number, because the mean of its divisors is an integer number (161950).

2⁶⁴³⁵⁴³ is an apocalyptic number.

643543 is a deficient number, since it is larger than the sum of its proper divisors (4257).

643543 is a wasteful number, since it uses less digits than its factorization.

643543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4256.

The product of its digits is 4320, while the sum is 25.

The square root of 643543 is about 802.2113187932. The cubic root of 643543 is about 86.3361192617.

Adding to 643543 its reverse (345346), we get a palindrome (988889).

The spelling of 643543 in words is "six hundred forty-three thousand, five hundred forty-three".