643720287 has 16 divisors (see below), whose sum is σ = 981374720. Its totient is φ = 367664832.

The previous prime is 643720271. The next prime is 643720291. The reversal of 643720287 is 782027346.

It is not a de Polignac number, because 643720287 - 2⁴ = 643720271 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 (643728287) 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 15 ways as a sum of consecutive naturals, for example, 47283 + ... + 59355.

It is an arithmetic number, because the mean of its divisors is an integer number (61335920).

Almost surely, 2^643720287 is an apocalyptic number.

643720287 is a deficient number, since it is larger than the sum of its proper divisors (337654433).

643720287 is a wasteful number, since it uses less digits than its factorization.

643720287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14622.

The product of its (nonzero) digits is 112896, while the sum is 39.

The square root of 643720287 is about 25371.6433641970. The cubic root of 643720287 is about 863.4404666058.

The spelling of 643720287 in words is "six hundred forty-three million, seven hundred twenty thousand, two hundred eighty-seven".