999916805 has 4 divisors (see below), whose sum is σ = 1199900172. Its totient is φ = 799933440.

The previous prime is 999916783. The next prime is 999916807. The reversal of 999916805 is 508619999.

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

It can be written as a sum of positive squares in 2 ways, for example, as 232959169 + 766957636 = 15263^2 + 27694^2 .

It is not a de Polignac number, because 999916805 - 2⁶ = 999916741 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999916807) 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, 99991676 + ... + 99991685.

It is an arithmetic number, because the mean of its divisors is an integer number (299975043).

Almost surely, 2^999916805 is an apocalyptic number.

It is an amenable number.

999916805 is a deficient number, since it is larger than the sum of its proper divisors (199983367).

999916805 is a wasteful number, since it uses less digits than its factorization.

999916805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199983366.

The product of its (nonzero) digits is 1574640, while the sum is 56.

The square root of 999916805 is about 31621.4611458737. The cubic root of 999916805 is about 999.9722675643.

The spelling of 999916805 in words is "nine hundred ninety-nine million, nine hundred sixteen thousand, eight hundred five".