643686873 has 12 divisors (see below), whose sum is σ = 873253680. Its totient is φ = 421630072.

The previous prime is 643686847. The next prime is 643686881. The reversal of 643686873 is 378686346.

It is a happy number.

It is not a de Polignac number, because 643686873 - 2⁹ = 643686361 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (643686973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 336586 + ... + 338492.

It is an arithmetic number, because the mean of its divisors is an integer number (72771140).

Almost surely, 2^643686873 is an apocalyptic number.

It is an amenable number.

643686873 is a deficient number, since it is larger than the sum of its proper divisors (229566807).

643686873 is an frugal number, since it uses more digits than its factorization.

643686873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3876 (or 1969 counting only the distinct ones).

The product of its digits is 3483648, while the sum is 51.

The square root of 643686873 is about 25370.9848646047. The cubic root of 643686873 is about 863.4255266287.

The spelling of 643686873 in words is "six hundred forty-three million, six hundred eighty-six thousand, eight hundred seventy-three".