21120320 has 56 divisors (see below), whose sum is σ = 54172104. Its totient is φ = 7796736.

The previous prime is 21120317. The next prime is 21120349. The reversal of 21120320 is 2302112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3748096 + 17372224 = 1936^2 + 4168^2 .

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1622 + ... + 6698.

It is an arithmetic number, because the mean of its divisors is an integer number (967359).

Almost surely, 2^21120320 is an apocalyptic number.

21120320 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 21120320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27086052).

21120320 is an abundant number, since it is smaller than the sum of its proper divisors (33051784).

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

21120320 is a wasteful number, since it uses less digits than its factorization.

21120320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5107 (or 5097 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21120320 is about 4595.6849326297. The cubic root of 21120320 is about 276.4183252385.

Adding to 21120320 its reverse (2302112), we get a palindrome (23422432).

The spelling of 21120320 in words is "twenty-one million, one hundred twenty thousand, three hundred twenty".