643018 has 4 divisors (see below), whose sum is σ = 964530. Its totient is φ = 321508.

The previous prime is 643009. The next prime is 643021. The reversal of 643018 is 810346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 613089 + 29929 = 783^2 + 173^2 .

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 643018.

It is an unprimeable number.

643018 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160753 + ... + 160756.

2⁶⁴³⁰¹⁸ is an apocalyptic number.

643018 is a deficient number, since it is larger than the sum of its proper divisors (321512).

643018 is a wasteful number, since it uses less digits than its factorization.

643018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321511.

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 643018 is about 801.8840315158. The cubic root of 643018 is about 86.3126353122.

The spelling of 643018 in words is "six hundred forty-three thousand, eighteen".