999643517823 has 4 divisors (see below), whose sum is σ = 1332858023768. Its totient is φ = 666429011880.

The previous prime is 999643517809. The next prime is 999643517843. The reversal of 999643517823 is 328715346999.

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

It is not a de Polignac number, because 999643517823 - 2¹⁰ = 999643516799 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 (999643517843) 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, 166607252968 + ... + 166607252973.

It is an arithmetic number, because the mean of its divisors is an integer number (333214505942).

Almost surely, 2^999643517823 is an apocalyptic number.

999643517823 is a deficient number, since it is larger than the sum of its proper divisors (333214505945).

999643517823 is a wasteful number, since it uses less digits than its factorization.

999643517823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333214505944.

The product of its digits is 88179840, while the sum is 66.

The spelling of 999643517823 in words is "nine hundred ninety-nine billion, six hundred forty-three million, five hundred seventeen thousand, eight hundred twenty-three".