20320440 has 128 divisors (see below), whose sum is σ = 73820160. Its totient is φ = 4368384.

The previous prime is 20320439. The next prime is 20320441. The reversal of 20320440 is 4402302.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (20320439) and next prime (20320441).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20320441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13569 + ... + 14991.

It is an arithmetic number, because the mean of its divisors is an integer number (576720).

Almost surely, 2^20320440 is an apocalyptic number.

20320440 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 20320440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36910080).

20320440 is an abundant number, since it is smaller than the sum of its proper divisors (53499720).

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

20320440 is a wasteful number, since it uses less digits than its factorization.

20320440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1461 (or 1457 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 15.

The square root of 20320440 is about 4507.8198721777. The cubic root of 20320440 is about 272.8837675576.

Adding to 20320440 its reverse (4402302), we get a palindrome (24722742).

The spelling of 20320440 in words is "twenty million, three hundred twenty thousand, four hundred forty".