20305 has 8 divisors (see below), whose sum is σ = 25344. Its totient is φ = 15600.

The previous prime is 20297. The next prime is 20323. The reversal of 20305 is 50302.

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

It is not a de Polignac number, because 20305 - 2³ = 20297 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20291 and 20300.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 90 + ... + 220.

It is an arithmetic number, because the mean of its divisors is an integer number (3168).

2²⁰³⁰⁵ is an apocalyptic number.

It is an amenable number.

20305 is a deficient number, since it is larger than the sum of its proper divisors (5039).

20305 is a wasteful number, since it uses less digits than its factorization.

20305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 167.

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

The square root of 20305 is about 142.4956139676. The cubic root of 20305 is about 27.2814635312.

Adding to 20305 its reverse (50302), we get a palindrome (70607).

It can be divided in two parts, 20 and 305, that added together give a triangular number (325 = T₂₅).

The spelling of 20305 in words is "twenty thousand, three hundred five".