643983 has 8 divisors (see below), whose sum is σ = 867888. Its totient is φ = 424704.

The previous prime is 643969. The next prime is 643991. The reversal of 643983 is 389346.

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

It is not a de Polignac number, because 643983 - 2⁶ = 643919 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643183) 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, 816 + ... + 1397.

It is an arithmetic number, because the mean of its divisors is an integer number (108486).

2⁶⁴³⁹⁸³ is an apocalyptic number.

643983 is a deficient number, since it is larger than the sum of its proper divisors (223905).

643983 is a wasteful number, since it uses less digits than its factorization.

643983 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2313.

The product of its digits is 15552, while the sum is 33.

The square root of 643983 is about 802.4855138879. The cubic root of 643983 is about 86.3557912122.

The spelling of 643983 in words is "six hundred forty-three thousand, nine hundred eighty-three".