643380391 has 4 divisors (see below), whose sum is σ = 643495392. Its totient is φ = 643265392.

The previous prime is 643380389. The next prime is 643380443. The reversal of 643380391 is 193083346.

643380391 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 643380391 - 2¹ = 643380389 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 643380391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643380301) 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, 48655 + ... + 60448.

It is an arithmetic number, because the mean of its divisors is an integer number (160873848).

Almost surely, 2^643380391 is an apocalyptic number.

643380391 is a deficient number, since it is larger than the sum of its proper divisors (115001).

643380391 is a wasteful number, since it uses less digits than its factorization.

643380391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115000.

The product of its (nonzero) digits is 46656, while the sum is 37.

The square root of 643380391 is about 25364.9441355584. The cubic root of 643380391 is about 863.2884691020.

The spelling of 643380391 in words is "six hundred forty-three million, three hundred eighty thousand, three hundred ninety-one".