643641370 has 32 divisors (see below), whose sum is σ = 1227759120. Its totient is φ = 242511360.

The previous prime is 643641353. The next prime is 643641371. The reversal of 643641370 is 73146346.

It can be written as a sum of positive squares in 8 ways, for example, as 2893401 + 640747969 = 1701^2 + 25313^2 .

It is not an unprimeable number, because it can be changed into a prime (643641371) 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 15 ways as a sum of consecutive naturals, for example, 15177 + ... + 38956.

Almost surely, 2^643641370 is an apocalyptic number.

643641370 is a deficient number, since it is larger than the sum of its proper divisors (584117750).

643641370 is a wasteful number, since it uses less digits than its factorization.

643641370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54210.

The product of its (nonzero) digits is 36288, while the sum is 34.

The square root of 643641370 is about 25370.0880960236. The cubic root of 643641370 is about 863.4051806193.

The spelling of 643641370 in words is "six hundred forty-three million, six hundred forty-one thousand, three hundred seventy".