643664256523633 has 16 divisors (see below), whose sum is σ = 652798724331600. Its totient is φ = 634591520188416.

The previous prime is 643664256523619. The next prime is 643664256523661. The reversal of 643664256523633 is 336325652466346.

643664256523633 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 111199724536384 + 532464531987249 = 10545128^2 + 23075193^2 .

It is a cyclic number.

It is not a de Polignac number, because 643664256523633 - 2²¹ = 643664254426481 is a prime.

It is a super-2 number, since 2×643664256523633² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643664256523033) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 99188893 + ... + 105478741.

It is an arithmetic number, because the mean of its divisors is an integer number (40799920270725).

Almost surely, 2^{643664256523633} is an apocalyptic number.

It is an amenable number.

643664256523633 is a deficient number, since it is larger than the sum of its proper divisors (9134467807967).

643664256523633 is a wasteful number, since it uses less digits than its factorization.

643664256523633 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6294756.

The product of its digits is 1007769600, while the sum is 64.

The spelling of 643664256523633 in words is "six hundred forty-three trillion, six hundred sixty-four billion, two hundred fifty-six million, five hundred twenty-three thousand, six hundred thirty-three".