643660753 has 2 divisors, whose sum is σ = 643660754. Its totient is φ = 643660752.

The previous prime is 643660741. The next prime is 643660813. The reversal of 643660753 is 357066346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 565107984 + 78552769 = 23772^2 + 8863^2 .

It is a cyclic number.

It is not a de Polignac number, because 643660753 - 2¹³ = 643652561 is a prime.

It is a super-3 number, since 3×643660753³ (a number of 27 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (643664753) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321830376 + 321830377.

It is an arithmetic number, because the mean of its divisors is an integer number (321830377).

Almost surely, 2^643660753 is an apocalyptic number.

It is an amenable number.

643660753 is a deficient number, since it is larger than the sum of its proper divisors (1).

643660753 is an equidigital number, since it uses as much as digits as its factorization.

643660753 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 272160, while the sum is 40.

The square root of 643660753 is about 25370.4700981279. The cubic root of 643660753 is about 863.4138475651.

The spelling of 643660753 in words is "six hundred forty-three million, six hundred sixty thousand, seven hundred fifty-three".