999844991 has 4 divisors (see below), whose sum is σ = 1000050000. Its totient is φ = 999639984.

The previous prime is 999844973. The next prime is 999845017. The reversal of 999844991 is 199448999.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199448999 = 1831 ⋅108929.

It is a cyclic number.

It is not a de Polignac number, because 999844991 - 2²² = 995650687 is a prime.

It is a Duffinian number.

999844991 is a modest number, since divided by 44991 gives 9998 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999874991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 95006 + ... + 105003.

It is an arithmetic number, because the mean of its divisors is an integer number (250012500).

Almost surely, 2^999844991 is an apocalyptic number.

999844991 is a deficient number, since it is larger than the sum of its proper divisors (205009).

999844991 is a wasteful number, since it uses less digits than its factorization.

999844991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205008.

The product of its digits is 7558272, while the sum is 62.

The square root of 999844991 is about 31620.3255992091. The cubic root of 999844991 is about 999.9483276633.

The spelling of 999844991 in words is "nine hundred ninety-nine million, eight hundred forty-four thousand, nine hundred ninety-one".