20503 has 8 divisors (see below), whose sum is σ = 24480. Its totient is φ = 16800.

The previous prime is 20483. The next prime is 20507. The reversal of 20503 is 30502.

20503 is a nontrivial binomial coefficient, being equal to C(203, 2).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20503 - 2⁹ = 19991 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a nialpdrome in base 9 and base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 20503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20507) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 153 + ... + 253.

It is an arithmetic number, because the mean of its divisors is an integer number (3060).

2²⁰⁵⁰³ is an apocalyptic number.

20503 is the 202-nd triangular number.

20503 is the 68-th centered nonagonal number.

20503 is a deficient number, since it is larger than the sum of its proper divisors (3977).

20503 is a wasteful number, since it uses less digits than its factorization.

20503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137.

The product of its (nonzero) digits is 30, while the sum is 10.

The square root of 20503 is about 143.1886867039. The cubic root of 20503 is about 27.3698533585.

Subtracting 20503 from its reverse (30502), we obtain a palindrome (9999).

The spelling of 20503 in words is "twenty thousand, five hundred three".