643338373 has 4 divisors (see below), whose sum is σ = 643878828. Its totient is φ = 642797920.

The previous prime is 643338337. The next prime is 643338379. The reversal of 643338373 is 373833346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 373833346 = 2 ⋅186916673.

It can be written as a sum of positive squares in 2 ways, for example, as 505440324 + 137898049 = 22482^2 + 11743^2 .

It is a cyclic number.

It is not a de Polignac number, because 643338373 - 2⁹ = 643337861 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643338379) 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 3 ways as a sum of consecutive naturals, for example, 268438 + ... + 270823.

It is an arithmetic number, because the mean of its divisors is an integer number (160969707).

Almost surely, 2^643338373 is an apocalyptic number.

It is an amenable number.

643338373 is a deficient number, since it is larger than the sum of its proper divisors (540455).

643338373 is a wasteful number, since it uses less digits than its factorization.

643338373 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 540454.

The product of its digits is 326592, while the sum is 40.

The square root of 643338373 is about 25364.1158529131. The cubic root of 643338373 is about 863.2696754277.

The spelling of 643338373 in words is "six hundred forty-three million, three hundred thirty-eight thousand, three hundred seventy-three".