643816873937 has 2 divisors, whose sum is σ = 643816873938. Its totient is φ = 643816873936.

The previous prime is 643816873901. The next prime is 643816873979. The reversal of 643816873937 is 739378618346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 643398098641 + 418775296 = 802121^2 + 20464^2 .

It is a cyclic number.

It is not a de Polignac number, because 643816873937 - 2⁸ = 643816873681 is a prime.

It is not a weakly prime, because it can be changed into another prime (643816875937) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321908436968 + 321908436969.

It is an arithmetic number, because the mean of its divisors is an integer number (321908436969).

Almost surely, 2^643816873937 is an apocalyptic number.

It is an amenable number.

643816873937 is a deficient number, since it is larger than the sum of its proper divisors (1).

643816873937 is an equidigital number, since it uses as much as digits as its factorization.

643816873937 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 109734912, while the sum is 65.

The spelling of 643816873937 in words is "six hundred forty-three billion, eight hundred sixteen million, eight hundred seventy-three thousand, nine hundred thirty-seven".