21144320 has 36 divisors (see below), whose sum is σ = 50650320. Its totient is φ = 8457216.

The previous prime is 21144307. The next prime is 21144323. The reversal of 21144320 is 2344112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6980 + ... + 9539.

Almost surely, 2^21144320 is an apocalyptic number.

21144320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21144320 is an abundant number, since it is smaller than the sum of its proper divisors (29506000).

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

21144320 is an equidigital number, since it uses as much as digits as its factorization.

21144320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16540 (or 16526 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21144320 is about 4598.2953363176. The cubic root of 21144320 is about 276.5229879288.

Adding to 21144320 its reverse (2344112), we get a palindrome (23488432).

The spelling of 21144320 in words is "twenty-one million, one hundred forty-four thousand, three hundred twenty".