990813 has 4 divisors (see below), whose sum is σ = 1321088. Its totient is φ = 660540.

The previous prime is 990809. The next prime is 990841. The reversal of 990813 is 318099.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 318099 = 3 ⋅106033.

It is not a de Polignac number, because 990813 - 2² = 990809 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

990813 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990893) 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, 165133 + ... + 165138.

It is an arithmetic number, because the mean of its divisors is an integer number (330272).

2⁹⁹⁰⁸¹³ is an apocalyptic number.

It is an amenable number.

990813 is a deficient number, since it is larger than the sum of its proper divisors (330275).

990813 is a wasteful number, since it uses less digits than its factorization.

990813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330274.

The product of its (nonzero) digits is 1944, while the sum is 30.

The square root of 990813 is about 995.3959011368. The cubic root of 990813 is about 99.6928240622.

The spelling of 990813 in words is "nine hundred ninety thousand, eight hundred thirteen".