999817217 has 10 divisors (see below), whose sum is σ = 1166386818. Its totient is φ = 856984128.

The previous prime is 999817201. The next prime is 999817241. The reversal of 999817217 is 712718999.

It can be written as a sum of positive squares in only one way, i.e., 995781136 + 4036081 = 31556^2 + 2009^2 .

It is not a de Polignac number, because 999817217 - 2⁴ = 999817201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (999817817) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 205808 + ... + 210609.

It is a Proth number, since it is equal to 1907 ⋅ 2¹⁹ + 1 and 1907 < 2¹⁹.

Almost surely, 2^999817217 is an apocalyptic number.

It is an amenable number.

999817217 is a deficient number, since it is larger than the sum of its proper divisors (166569601).

999817217 is an frugal number, since it uses more digits than its factorization.

999817217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416445 (or 416424 counting only the distinct ones).

The product of its digits is 571536, while the sum is 53.

The square root of 999817217 is about 31619.8864166208. The cubic root of 999817217 is about 999.9390686208.

The spelling of 999817217 in words is "nine hundred ninety-nine million, eight hundred seventeen thousand, two hundred seventeen".