20381440 has 36 divisors (see below), whose sum is σ = 48822984. Its totient is φ = 8152064.

The previous prime is 20381411. The next prime is 20381443. The reversal of 20381440 is 4418302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20381443) 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 3 ways as a sum of consecutive naturals, for example, 6682 + ... + 9241.

It is an arithmetic number, because the mean of its divisors is an integer number (1356194).

Almost surely, 2^20381440 is an apocalyptic number.

20381440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20381440 is an abundant number, since it is smaller than the sum of its proper divisors (28441544).

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

20381440 is an equidigital number, since it uses as much as digits as its factorization.

20381440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15944 (or 15930 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 20381440 is about 4514.5808221805. The cubic root of 20381440 is about 273.1565516947.

Adding to 20381440 its reverse (4418302), we get a palindrome (24799742).

The spelling of 20381440 in words is "twenty million, three hundred eighty-one thousand, four hundred forty".