20424 has 32 divisors (see below), whose sum is σ = 54720. Its totient is φ = 6336.

The previous prime is 20411. The next prime is 20431. The reversal of 20424 is 42402.

20424 is nontrivially palindromic in base 9.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a plaindrome in base 7.

It is a zygodrome in base 7.

It is an unprimeable number.

20424 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 7 ways as a sum of consecutive naturals, for example, 534 + ... + 570.

It is an arithmetic number, because the mean of its divisors is an integer number (1710).

2²⁰⁴²⁴ is an apocalyptic number.

20424 is a gapful number since it is divisible by the number (24) 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 20424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27360).

20424 is an abundant number, since it is smaller than the sum of its proper divisors (34296).

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

20424 is a wasteful number, since it uses less digits than its factorization.

20424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69 (or 65 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 12.

The square root of 20424 is about 142.9125606796. The cubic root of 20424 is about 27.3346552338.

Adding to 20424 its reverse (42402), we get a palindrome (62826).

It can be divided in two parts, 20 and 424, that added together give a palindrome (444).

The spelling of 20424 in words is "twenty thousand, four hundred twenty-four", and thus it is an iban number.