643501673 has 4 divisors (see below), whose sum is σ = 655643268. Its totient is φ = 631360080.

The previous prime is 643501657. The next prime is 643501687. The reversal of 643501673 is 376105346.

643501673 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, and also an emirpimes, since its reverse is a distinct semiprime: 376105346 = 2 ⋅188052673.

It can be written as a sum of positive squares in 2 ways, for example, as 222964624 + 420537049 = 14932^2 + 20507^2 .

It is a cyclic number.

It is not a de Polignac number, because 643501673 - 2⁴ = 643501657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643501693) 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, 6070718 + ... + 6070823.

It is an arithmetic number, because the mean of its divisors is an integer number (163910817).

Almost surely, 2^643501673 is an apocalyptic number.

It is an amenable number.

643501673 is a deficient number, since it is larger than the sum of its proper divisors (12141595).

643501673 is a wasteful number, since it uses less digits than its factorization.

643501673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12141594.

The product of its (nonzero) digits is 45360, while the sum is 35.

The square root of 643501673 is about 25367.3347634315. The cubic root of 643501673 is about 863.3427111312.

The spelling of 643501673 in words is "six hundred forty-three million, five hundred one thousand, six hundred seventy-three".