20240 has 40 divisors (see below), whose sum is σ = 53568. Its totient is φ = 7040.

The previous prime is 20233. The next prime is 20249. The reversal of 20240 is 4202.

20240 is nontrivially palindromic in base 15.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (8).

It is not an unprimeable number, because it can be changed into a prime (20249) by changing a digit.

20240 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, 869 + ... + 891.

2²⁰²⁴⁰ is an apocalyptic number.

20240 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 20240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26784).

20240 is an abundant number, since it is smaller than the sum of its proper divisors (33328).

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

20240 is a wasteful number, since it uses less digits than its factorization.

20240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47 (or 41 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 8.

The square root of 20240 is about 142.2673539502. The cubic root of 20240 is about 27.2523214362.

Adding to 20240 its reverse (4202), we get a palindrome (24442).

It can be divided in two parts, 202 and 40, that added together give a palindrome (242).

The spelling of 20240 in words is "twenty thousand, two hundred forty", and thus it is an iban number.