643659 has 8 divisors (see below), whose sum is σ = 879312. Its totient is φ = 418560.

The previous prime is 643651. The next prime is 643661. The reversal of 643659 is 956346.

It is a happy number.

643659 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.

It is not a de Polignac number, because 643659 - 2³ = 643651 is a prime.

It is a nialpdrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (643651) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2494 + ... + 2739.

It is an arithmetic number, because the mean of its divisors is an integer number (109914).

2⁶⁴³⁶⁵⁹ is an apocalyptic number.

643659 is a deficient number, since it is larger than the sum of its proper divisors (235653).

643659 is a wasteful number, since it uses less digits than its factorization.

643659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5277.

The product of its digits is 19440, while the sum is 33.

The square root of 643659 is about 802.2836156871. The cubic root of 643659 is about 86.3413063733.

The spelling of 643659 in words is "six hundred forty-three thousand, six hundred fifty-nine".