20340 has 36 divisors (see below), whose sum is σ = 62244. Its totient is φ = 5376.

The previous prime is 20333. The next prime is 20341. The reversal of 20340 is 4302.

It can be written as a sum of positive squares in 2 ways, for example, as 2916 + 17424 = 54^2 + 132^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (9).

20340 is an undulating number in base 15.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20341) by changing a digit.

20340 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 124 + ... + 236.

It is an arithmetic number, because the mean of its divisors is an integer number (1729).

2²⁰³⁴⁰ is an apocalyptic number.

20340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31122).

20340 is an abundant number, since it is smaller than the sum of its proper divisors (41904).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20340 is a wasteful number, since it uses less digits than its factorization.

20340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128 (or 123 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 9.

The square root of 20340 is about 142.6183718881. The cubic root of 20340 is about 27.2971296745.

Adding to 20340 its reverse (4302), we get a palindrome (24642).

It can be divided in two parts, 203 and 40, that added together give a 5-th power (243 = 3⁵).

The spelling of 20340 in words is "twenty thousand, three hundred forty", and thus it is an iban number.