643945617 has 24 divisors (see below), whose sum is σ = 1069184064. Its totient is φ = 365835744.

The previous prime is 643945591. The next prime is 643945619. The reversal of 643945617 is 716549346.

It is not a de Polignac number, because 643945617 - 2¹⁴ = 643929233 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643945619) 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 23 ways as a sum of consecutive naturals, for example, 18643 + ... + 40440.

It is an arithmetic number, because the mean of its divisors is an integer number (44549336).

Almost surely, 2^643945617 is an apocalyptic number.

It is an amenable number.

643945617 is a deficient number, since it is larger than the sum of its proper divisors (425238447).

643945617 is a wasteful number, since it uses less digits than its factorization.

643945617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59269 (or 59266 counting only the distinct ones).

The product of its digits is 544320, while the sum is 45.

The square root of 643945617 is about 25376.0835630717. The cubic root of 643945617 is about 863.5412020480.

The spelling of 643945617 in words is "six hundred forty-three million, nine hundred forty-five thousand, six hundred seventeen".