813999 has 4 divisors (see below), whose sum is σ = 1085336. Its totient is φ = 542664.

The previous prime is 813997. The next prime is 814003. The reversal of 813999 is 999318.

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

It is not a de Polignac number, because 813999 - 2¹ = 813997 is a prime.

It is a D-number.

It is a Duffinian number.

813999 is a modest number, since divided by 999 gives 813 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (813991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135664 + ... + 135669.

It is an arithmetic number, because the mean of its divisors is an integer number (271334).

2⁸¹³⁹⁹⁹ is an apocalyptic number.

813999 is a deficient number, since it is larger than the sum of its proper divisors (271337).

813999 is a wasteful number, since it uses less digits than its factorization.

813999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 271336.

The product of its digits is 17496, while the sum is 39.

The square root of 813999 is about 902.2189313022. The cubic root of 813999 is about 93.3701286327.

The spelling of 813999 in words is "eight hundred thirteen thousand, nine hundred ninety-nine".