21623328 has 96 divisors (see below), whose sum is σ = 65318400. Its totient is φ = 6951168.

The previous prime is 21623321. The next prime is 21623347. The reversal of 21623328 is 82332612.

21623328 is a `hidden beast` number, since 2 + 1 + 623 + 32 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (96).

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

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21623321) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24625 + ... + 25487.

It is an arithmetic number, because the mean of its divisors is an integer number (680400).

Almost surely, 2^21623328 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21623328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32659200).

21623328 is an abundant number, since it is smaller than the sum of its proper divisors (43695072).

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

21623328 is a wasteful number, since it uses less digits than its factorization.

21623328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 911 (or 897 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 21623328 is about 4650.0890314057. The cubic root of 21623328 is about 278.5955522642.

The spelling of 21623328 in words is "twenty-one million, six hundred twenty-three thousand, three hundred twenty-eight".