643661253325205 has 16 divisors (see below), whose sum is σ = 788828932744704. Its totient is φ = 503972092502400.

The previous prime is 643661253325147. The next prime is 643661253325229. The reversal of 643661253325205 is 502523352166346.

It is a happy number.

It is not a de Polignac number, because 643661253325205 - 2⁶ = 643661253325141 is a prime.

It is a Duffinian 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 15 ways as a sum of consecutive naturals, for example, 134250305 + ... + 138962105.

It is an arithmetic number, because the mean of its divisors is an integer number (49301808296544).

Almost surely, 2^{643661253325205} is an apocalyptic number.

It is an amenable number.

643661253325205 is a deficient number, since it is larger than the sum of its proper divisors (145167679419499).

643661253325205 is a wasteful number, since it uses less digits than its factorization.

643661253325205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5293156.

The product of its (nonzero) digits is 23328000, while the sum is 53.

The spelling of 643661253325205 in words is "six hundred forty-three trillion, six hundred sixty-one billion, two hundred fifty-three million, three hundred twenty-five thousand, two hundred five".