999317991 has 8 divisors (see below), whose sum is σ = 1522770304. Its totient is φ = 571038840.

The previous prime is 999317929. The next prime is 999318037. The reversal of 999317991 is 199713999.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 999317991 - 2¹⁹ = 998793703 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 (999317591) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23793265 + ... + 23793306.

It is an arithmetic number, because the mean of its divisors is an integer number (190346288).

Almost surely, 2^999317991 is an apocalyptic number.

999317991 is a deficient number, since it is larger than the sum of its proper divisors (523452313).

999317991 is a wasteful number, since it uses less digits than its factorization.

999317991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47586581.

The product of its digits is 1240029, while the sum is 57.

The square root of 999317991 is about 31611.9912533203. The cubic root of 999317991 is about 999.7726119653.

The spelling of 999317991 in words is "nine hundred ninety-nine million, three hundred seventeen thousand, nine hundred ninety-one".