643722266879999 has 4 divisors (see below), whose sum is σ = 643988597981664. Its totient is φ = 643455935778336.

The previous prime is 643722266879971. The next prime is 643722266880013. The reversal of 643722266879999 is 999978662227346.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 643722266879999 - 2⁸ = 643722266879743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643722266879099) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133165547207 + ... + 133165552040.

It is an arithmetic number, because the mean of its divisors is an integer number (160997149495416).

Almost surely, 2^{643722266879999} is an apocalyptic number.

643722266879999 is a deficient number, since it is larger than the sum of its proper divisors (266331101665).

643722266879999 is a wasteful number, since it uses less digits than its factorization.

643722266879999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 266331101664.

The product of its digits is 53331167232, while the sum is 89.

The spelling of 643722266879999 in words is "six hundred forty-three trillion, seven hundred twenty-two billion, two hundred sixty-six million, eight hundred seventy-nine thousand, nine hundred ninety-nine".