643745856005 has 32 divisors (see below), whose sum is σ = 913143103488. Its totient is φ = 426336552000.

The previous prime is 643745855971. The next prime is 643745856041. The reversal of 643745856005 is 500658547346.

It is a happy number.

It is not a de Polignac number, because 643745856005 - 2⁸ = 643745855749 is a prime.

It is a super-2 number, since 2×643745856005² (a number of 24 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 44021 + ... + 1135530.

It is an arithmetic number, because the mean of its divisors is an integer number (28535721984).

Almost surely, 2^643745856005 is an apocalyptic number.

It is an amenable number.

643745856005 is a deficient number, since it is larger than the sum of its proper divisors (269397247483).

643745856005 is a wasteful number, since it uses less digits than its factorization.

643745856005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1180097.

The product of its (nonzero) digits is 12096000, while the sum is 53.

The spelling of 643745856005 in words is "six hundred forty-three billion, seven hundred forty-five million, eight hundred fifty-six thousand, five".