643940529 has 4 divisors (see below), whose sum is σ = 858587376. Its totient is φ = 429293684.

The previous prime is 643940527. The next prime is 643940537. The reversal of 643940529 is 925049346.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 643940529 - 2¹ = 643940527 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643940527) 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, 107323419 + ... + 107323424.

It is an arithmetic number, because the mean of its divisors is an integer number (214646844).

Almost surely, 2^643940529 is an apocalyptic number.

It is an amenable number.

643940529 is a deficient number, since it is larger than the sum of its proper divisors (214646847).

643940529 is a wasteful number, since it uses less digits than its factorization.

643940529 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214646846.

The product of its (nonzero) digits is 233280, while the sum is 42.

The square root of 643940529 is about 25375.9833109970. The cubic root of 643940529 is about 863.5389276793.

The spelling of 643940529 in words is "six hundred forty-three million, nine hundred forty thousand, five hundred twenty-nine".