643539 has 16 divisors (see below), whose sum is σ = 957600. Its totient is φ = 381696.

The previous prime is 643523. The next prime is 643547. The reversal of 643539 is 935346.

It is a happy number.

It is not a de Polignac number, because 643539 - 2⁴ = 643523 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643589) by changing a digit.

It is a nontrivial repunit in base 86.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 847 + ... + 1415.

It is an arithmetic number, because the mean of its divisors is an integer number (59850).

2⁶⁴³⁵³⁹ is an apocalyptic number.

643539 is a deficient number, since it is larger than the sum of its proper divisors (314061).

643539 is a wasteful number, since it uses less digits than its factorization.

643539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 614.

The product of its digits is 9720, while the sum is 30.

The square root of 643539 is about 802.2088256807. The cubic root of 643539 is about 86.3359403846.

The spelling of 643539 in words is "six hundred forty-three thousand, five hundred thirty-nine".