643889799 has 24 divisors (see below), whose sum is σ = 1091660960. Its totient is φ = 357991488.

The previous prime is 643889791. The next prime is 643889819. The reversal of 643889799 is 997988346.

643889799 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 643889799 - 2³ = 643889791 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643889791) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 135784 + ... + 140445.

Almost surely, 2^643889799 is an apocalyptic number.

643889799 is a deficient number, since it is larger than the sum of its proper divisors (447771161).

643889799 is a wasteful number, since it uses less digits than its factorization.

643889799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276279 (or 276276 counting only the distinct ones).

The product of its digits is 23514624, while the sum is 63.

The square root of 643889799 is about 25374.9837241327. The cubic root of 643889799 is about 863.5162503884.

The spelling of 643889799 in words is "six hundred forty-three million, eight hundred eighty-nine thousand, seven hundred ninety-nine".