643605 has 16 divisors (see below), whose sum is σ = 1041984. Its totient is φ = 339200.

The previous prime is 643589. The next prime is 643619. The reversal of 643605 is 506346.

It is not a de Polignac number, because 643605 - 2⁴ = 643589 is a prime.

It is a nialpdrome in base 15.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1405 + ... + 1805.

It is an arithmetic number, because the mean of its divisors is an integer number (65124).

2⁶⁴³⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

643605 is a deficient number, since it is larger than the sum of its proper divisors (398379).

643605 is a wasteful number, since it uses less digits than its factorization.

643605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 516.

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

The square root of 643605 is about 802.2499610471. The cubic root of 643605 is about 86.3388917609.

The spelling of 643605 in words is "six hundred forty-three thousand, six hundred five".