20003 has 4 divisors (see below), whose sum is σ = 20328. Its totient is φ = 19680.

The previous prime is 19997. The next prime is 20011. The reversal of 20003 is 30002.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20003 - 2¹⁰ = 18979 is a prime.

It is a Duffinian number.

20003 is a modest number, since divided by 3 gives 2 as remainder.

It is not an unprimeable number, because it can be changed into a prime (20023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38 + ... + 203.

It is an arithmetic number, because the mean of its divisors is an integer number (5082).

2²⁰⁰⁰³ is an apocalyptic number.

20003 is a deficient number, since it is larger than the sum of its proper divisors (325).

20003 is an equidigital number, since it uses as much as digits as its factorization.

20003 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324.

The product of its (nonzero) digits is 6, while the sum is 5.

The square root of 20003 is about 141.4319624413. The cubic root of 20003 is about 27.1455333069.

Adding to 20003 its reverse (30002), we get a palindrome (50005).

Subtracting 20003 from its reverse (30002), we obtain a palindrome (9999).

The spelling of 20003 in words is "twenty thousand, three", and thus it is an iban number.