21040320 has 224 divisors, whose sum is σ = 79589376. Its totient is φ = 4608000.

The previous prime is 21040297. The next prime is 21040387. The reversal of 21040320 is 2304012.

It is a tau number, because it is divible by the number of its divisors (224).

It is a super-3 number, since 3×21040320³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21040296 and 21040305.

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 31 ways as a sum of consecutive naturals, for example, 208270 + ... + 208370.

Almost surely, 2^21040320 is an apocalyptic number.

21040320 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 21040320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39794688).

21040320 is an abundant number, since it is smaller than the sum of its proper divisors (58549056).

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

21040320 is a wasteful number, since it uses less digits than its factorization.

21040320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 12.

The square root of 21040320 is about 4586.9728579969. The cubic root of 21040320 is about 276.0688759003.

Adding to 21040320 its reverse (2304012), we get a palindrome (23344332).

The spelling of 21040320 in words is "twenty-one million, forty thousand, three hundred twenty".