643808345 has 4 divisors (see below), whose sum is σ = 772570020. Its totient is φ = 515046672.

The previous prime is 643808299. The next prime is 643808351. The reversal of 643808345 is 543808346.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 259177801 + 384630544 = 16099^2 + 19612^2 .

It is a cyclic number.

It is not a de Polignac number, because 643808345 - 2⁸ = 643808089 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64380830 + ... + 64380839.

It is an arithmetic number, because the mean of its divisors is an integer number (193142505).

Almost surely, 2^643808345 is an apocalyptic number.

It is an amenable number.

643808345 is a deficient number, since it is larger than the sum of its proper divisors (128761675).

643808345 is a wasteful number, since it uses less digits than its factorization.

643808345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128761674.

The product of its (nonzero) digits is 276480, while the sum is 41.

The square root of 643808345 is about 25373.3786674144. The cubic root of 643808345 is about 863.4798363835.

Subtracting from 643808345 its reverse (543808346), we obtain a palindrome (99999999).

The spelling of 643808345 in words is "six hundred forty-three million, eight hundred eight thousand, three hundred forty-five".