21928320 has 224 divisors, whose sum is σ = 80269920. Its totient is φ = 5723136.

The previous prime is 21928303. The next prime is 21928327. The reversal of 21928320 is 2382912.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21928327) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 466537 + ... + 466583.

Almost surely, 2^21928320 is an apocalyptic number.

21928320 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 21928320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40134960).

21928320 is an abundant number, since it is smaller than the sum of its proper divisors (58341600).

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

21928320 is an frugal number, since it uses more digits than its factorization.

21928320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 57 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21928320 is about 4682.7684119546. The cubic root of 21928320 is about 279.8992835043.

The spelling of 21928320 in words is "twenty-one million, nine hundred twenty-eight thousand, three hundred twenty".