20623 has 4 divisors (see below), whose sum is σ = 21168. Its totient is φ = 20080.

The previous prime is 20611. The next prime is 20627. The reversal of 20623 is 32602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 32602 = 2 ⋅16301.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20623 is a prime.

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20627) 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, 211 + ... + 292.

It is an arithmetic number, because the mean of its divisors is an integer number (5292).

2²⁰⁶²³ is an apocalyptic number.

20623 is a deficient number, since it is larger than the sum of its proper divisors (545).

20623 is an equidigital number, since it uses as much as digits as its factorization.

20623 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 544.

The product of its (nonzero) digits is 72, while the sum is 13.

The square root of 20623 is about 143.6071028884. The cubic root of 20623 is about 27.4231463001.

The spelling of 20623 in words is "twenty thousand, six hundred twenty-three".