643867 has 8 divisors (see below), whose sum is σ = 748800. Its totient is φ = 542184.

The previous prime is 643859. The next prime is 643873. The reversal of 643867 is 768346.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643867 - 2³ = 643859 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 7.

It is not an unprimeable number, because it can be changed into a prime (643847) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 367 + ... + 1192.

It is an arithmetic number, because the mean of its divisors is an integer number (93600).

2⁶⁴³⁸⁶⁷ is an apocalyptic number.

643867 is a deficient number, since it is larger than the sum of its proper divisors (104933).

643867 is a wasteful number, since it uses less digits than its factorization.

643867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1625.

The product of its digits is 24192, while the sum is 34.

The square root of 643867 is about 802.4132351850. The cubic root of 643867 is about 86.3506058407.

The spelling of 643867 in words is "six hundred forty-three thousand, eight hundred sixty-seven".