20404440 has 128 divisors (see below), whose sum is σ = 77760000. Its totient is φ = 4662144.

The previous prime is 20404421. The next prime is 20404441. The reversal of 20404440 is 4440402.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20404441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6211 + ... + 8909.

It is an arithmetic number, because the mean of its divisors is an integer number (607500).

Almost surely, 2^20404440 is an apocalyptic number.

20404440 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 20404440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38880000).

20404440 is an abundant number, since it is smaller than the sum of its proper divisors (57355560).

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

20404440 is a wasteful number, since it uses less digits than its factorization.

20404440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2726 (or 2716 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 18.

The square root of 20404440 is about 4517.1274057746. The cubic root of 20404440 is about 273.2592634251.

Adding to 20404440 its reverse (4440402), we get a palindrome (24844842).

The spelling of 20404440 in words is "twenty million, four hundred four thousand, four hundred forty".