643399 has 4 divisors (see below), whose sum is σ = 681264. Its totient is φ = 605536.

The previous prime is 643373. The next prime is 643403. The reversal of 643399 is 993346.

643399 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 643399 - 2¹³ = 635207 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643369) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18907 + ... + 18940.

It is an arithmetic number, because the mean of its divisors is an integer number (170316).

2⁶⁴³³⁹⁹ is an apocalyptic number.

643399 is a deficient number, since it is larger than the sum of its proper divisors (37865).

643399 is a wasteful number, since it uses less digits than its factorization.

643399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37864.

The product of its digits is 17496, while the sum is 34.

The square root of 643399 is about 802.1215618595. The cubic root of 643399 is about 86.3296792214.

The spelling of 643399 in words is "six hundred forty-three thousand, three hundred ninety-nine".