643641057 has 24 divisors (see below), whose sum is σ = 946790208. Its totient is φ = 421260000.

The previous prime is 643641043. The next prime is 643641067. The reversal of 643641057 is 750146346.

It is a happy number.

643641057 is a `hidden beast` number, since 6 + 4 + 3 + 641 + 0 + 5 + 7 = 666.

It is not a de Polignac number, because 643641057 - 2⁴ = 643641041 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643641007) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 158383 + ... + 162395.

It is an arithmetic number, because the mean of its divisors is an integer number (39449592).

Almost surely, 2^643641057 is an apocalyptic number.

It is an amenable number.

643641057 is a deficient number, since it is larger than the sum of its proper divisors (303149151).

643641057 is a wasteful number, since it uses less digits than its factorization.

643641057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4341 (or 4338 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The square root of 643641057 is about 25370.0819273411. The cubic root of 643641057 is about 863.4050406625.

The spelling of 643641057 in words is "six hundred forty-three million, six hundred forty-one thousand, fifty-seven".