20523 has 4 divisors (see below), whose sum is σ = 27368. Its totient is φ = 13680.

The previous prime is 20521. The next prime is 20533. The reversal of 20523 is 32502.

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

It is not a de Polignac number, because 20523 - 2¹ = 20521 is a prime.

It is a D-number.

It is a Duffinian number.

It is a plaindrome in base 7 and base 11.

It is a nialpdrome in base 12.

It is a junction number, because it is equal to n+sod(n) for n = 20499 and 20508.

It is not an unprimeable number, because it can be changed into a prime (20521) 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, 3418 + ... + 3423.

It is an arithmetic number, because the mean of its divisors is an integer number (6842).

2²⁰⁵²³ is an apocalyptic number.

20523 is a deficient number, since it is larger than the sum of its proper divisors (6845).

20523 is an equidigital number, since it uses as much as digits as its factorization.

20523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6844.

The product of its (nonzero) digits is 60, while the sum is 12.

The square root of 20523 is about 143.2585076008. The cubic root of 20523 is about 27.3787499294.

The spelling of 20523 in words is "twenty thousand, five hundred twenty-three".