643395591 has 6 divisors (see below), whose sum is σ = 929349200. Its totient is φ = 428930388.

The previous prime is 643395547. The next prime is 643395619. The reversal of 643395591 is 195593346.

643395591 is a `hidden beast` number, since 64 + 3 + 39 + 559 + 1 = 666.

It is not a de Polignac number, because 643395591 - 2¹⁷ = 643264519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643395191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 35744191 + ... + 35744208.

Almost surely, 2^643395591 is an apocalyptic number.

643395591 is a deficient number, since it is larger than the sum of its proper divisors (285953609).

643395591 is a wasteful number, since it uses less digits than its factorization.

643395591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71488405 (or 71488402 counting only the distinct ones).

The product of its digits is 437400, while the sum is 45.

The square root of 643395591 is about 25365.2437599168. The cubic root of 643395591 is about 863.2952675070.

The spelling of 643395591 in words is "six hundred forty-three million, three hundred ninety-five thousand, five hundred ninety-one".