643293657 has 14 divisors (see below), whose sum is σ = 964500362. Its totient is φ = 428861952.

The previous prime is 643293619. The next prime is 643293667. The reversal of 643293657 is 756392346.

It can be written as a sum of positive squares in only one way, i.e., 626450841 + 16842816 = 25029^2 + 4104^2 .

It is not a de Polignac number, because 643293657 - 2¹¹ = 643291609 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 (643293667) 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 13 ways as a sum of consecutive naturals, for example, 440488 + ... + 441945.

It is an arithmetic number, because the mean of its divisors is an integer number (68892883).

Almost surely, 2^643293657 is an apocalyptic number.

It is an amenable number.

643293657 is a deficient number, since it is larger than the sum of its proper divisors (321206705).

643293657 is an frugal number, since it uses more digits than its factorization.

643293657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 882451 (or 882436 counting only the distinct ones).

The product of its digits is 816480, while the sum is 45.

The square root of 643293657 is about 25363.2343560517. The cubic root of 643293657 is about 863.2496741019.

The spelling of 643293657 in words is "six hundred forty-three million, two hundred ninety-three thousand, six hundred fifty-seven".