18813 has 4 divisors (see below), whose sum is σ = 25088. Its totient is φ = 12540.

The previous prime is 18803. The next prime is 18839. The reversal of 18813 is 31881.

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: 31881 = 3 ⋅10627.

It is not a de Polignac number, because 18813 - 2⁴ = 18797 is a prime.

It is a D-number.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 18813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18803) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3133 + ... + 3138.

It is an arithmetic number, because the mean of its divisors is an integer number (6272).

2¹⁸⁸¹³ is an apocalyptic number.

It is an amenable number.

18813 is a deficient number, since it is larger than the sum of its proper divisors (6275).

18813 is an equidigital number, since it uses as much as digits as its factorization.

18813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6274.

The product of its digits is 192, while the sum is 21.

The square root of 18813 is about 137.1604899379. The cubic root of 18813 is about 26.5961854066.

The spelling of 18813 in words is "eighteen thousand, eight hundred thirteen".