643500321 has 4 divisors (see below), whose sum is σ = 858000432. Its totient is φ = 429000212.

The previous prime is 643500313. The next prime is 643500323. The reversal of 643500321 is 123005346.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 643500321 - 2³ = 643500313 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643500291 and 643500300.

It is not an unprimeable number, because it can be changed into a prime (643500323) 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, 107250051 + ... + 107250056.

It is an arithmetic number, because the mean of its divisors is an integer number (214500108).

Almost surely, 2^643500321 is an apocalyptic number.

It is an amenable number.

643500321 is a deficient number, since it is larger than the sum of its proper divisors (214500111).

643500321 is a wasteful number, since it uses less digits than its factorization.

643500321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214500110.

The product of its (nonzero) digits is 2160, while the sum is 24.

The square root of 643500321 is about 25367.3081149735. The cubic root of 643500321 is about 863.3421065017.

Adding to 643500321 its reverse (123005346), we get a palindrome (766505667).

The spelling of 643500321 in words is "six hundred forty-three million, five hundred thousand, three hundred twenty-one".