643257857 has 4 divisors (see below), whose sum is σ = 701735856. Its totient is φ = 584779860.

The previous prime is 643257851. The next prime is 643257869. The reversal of 643257857 is 758752346.

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 643257857 - 2¹⁸ = 642995713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643257851) 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, 29238983 + ... + 29239004.

It is an arithmetic number, because the mean of its divisors is an integer number (175433964).

Almost surely, 2^643257857 is an apocalyptic number.

It is an amenable number.

643257857 is a deficient number, since it is larger than the sum of its proper divisors (58477999).

643257857 is a wasteful number, since it uses less digits than its factorization.

643257857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58477998.

The product of its digits is 1411200, while the sum is 47.

The square root of 643257857 is about 25362.5286002796. The cubic root of 643257857 is about 863.2336602067.

The spelling of 643257857 in words is "six hundred forty-three million, two hundred fifty-seven thousand, eight hundred fifty-seven".