643108327821 has 12 divisors (see below), whose sum is σ = 931089556800. Its totient is φ = 427744128840.

The previous prime is 643108327787. The next prime is 643108327831. The reversal of 643108327821 is 128723801346.

643108327821 is a `hidden beast` number, since 6 + 4 + 310 + 8 + 327 + 8 + 2 + 1 = 666.

It is not a de Polignac number, because 643108327821 - 2¹⁰ = 643108326797 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643108327831) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 82892271 + ... + 82900028.

It is an arithmetic number, because the mean of its divisors is an integer number (77590796400).

Almost surely, 2^643108327821 is an apocalyptic number.

It is an amenable number.

643108327821 is a deficient number, since it is larger than the sum of its proper divisors (287981228979).

643108327821 is a wasteful number, since it uses less digits than its factorization.

643108327821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165792736 (or 165792733 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 45.

The spelling of 643108327821 in words is "six hundred forty-three billion, one hundred eight million, three hundred twenty-seven thousand, eight hundred twenty-one".