643506593 has 4 divisors (see below), whose sum is σ = 681359940. Its totient is φ = 605653248.

The previous prime is 643506571. The next prime is 643506599. The reversal of 643506593 is 395605346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 497869969 + 145636624 = 22313^2 + 12068^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643506593 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 643506593.

It is not an unprimeable number, because it can be changed into a prime (643506599) 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 3 ways as a sum of consecutive naturals, for example, 18926648 + ... + 18926681.

It is an arithmetic number, because the mean of its divisors is an integer number (170339985).

Almost surely, 2^643506593 is an apocalyptic number.

It is an amenable number.

643506593 is a deficient number, since it is larger than the sum of its proper divisors (37853347).

643506593 is a wasteful number, since it uses less digits than its factorization.

643506593 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37853346.

The product of its (nonzero) digits is 291600, while the sum is 41.

The square root of 643506593 is about 25367.4317383530. The cubic root of 643506593 is about 863.3449114027.

The spelling of 643506593 in words is "six hundred forty-three million, five hundred six thousand, five hundred ninety-three".