499999991 has 16 divisors (see below), whose sum is σ = 547430400. Its totient is φ = 454860000.

The previous prime is 499999931. The next prime is 499999993. The reversal of 499999991 is 199999994.

It is not a de Polignac number, because 499999991 - 2¹⁴ = 499983607 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 (499999993) 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 15 ways as a sum of consecutive naturals, for example, 102866 + ... + 107616.

It is an arithmetic number, because the mean of its divisors is an integer number (34214400).

Almost surely, 2^499999991 is an apocalyptic number.

499999991 is a deficient number, since it is larger than the sum of its proper divisors (47430409).

499999991 is a wasteful number, since it uses less digits than its factorization.

499999991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4990.

The product of its digits is 19131876, while the sum is 68.

The square root of 499999991 is about 22360.6795737518. The cubic root of 499999991 is about 793.7005212219.

The spelling of 499999991 in words is "four hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred ninety-one".