20040 has 32 divisors (see below), whose sum is σ = 60480. Its totient is φ = 5312.

The previous prime is 20029. The next prime is 20047. The reversal of 20040 is 4002.

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a plaindrome in base 7.

It is a nialpdrome in base 12.

It is a zygodrome in base 7.

It is not an unprimeable number, because it can be changed into a prime (20047) by changing a digit.

20040 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, 37 + ... + 203.

It is an arithmetic number, because the mean of its divisors is an integer number (1890).

2²⁰⁰⁴⁰ is an apocalyptic number.

20040 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 20040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30240).

20040 is an abundant number, since it is smaller than the sum of its proper divisors (40440).

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

20040 is a wasteful number, since it uses less digits than its factorization.

20040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 181 (or 177 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 6.

The square root of 20040 is about 141.5627069535. The cubic root of 20040 is about 27.1622602327.

Adding to 20040 its reverse (4002), we get a palindrome (24042).

It can be divided in two parts, 200 and 40, that multiplied together give a cube (8000 = 20³).

The spelling of 20040 in words is "twenty thousand, forty", and thus it is an iban number.