21232320 has 112 divisors (see below), whose sum is σ = 71432928. Its totient is φ = 5324800.

The previous prime is 21232307. The next prime is 21232363. The reversal of 21232320 is 2323212.

It is a super-2 number, since 2×21232320² = 901622825164800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21232320.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15670 + ... + 16970.

It is an arithmetic number, because the mean of its divisors is an integer number (637794).

Almost surely, 2^21232320 is an apocalyptic number.

21232320 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 21232320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35716464).

21232320 is an abundant number, since it is smaller than the sum of its proper divisors (50200608).

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

21232320 is a wasteful number, since it uses less digits than its factorization.

21232320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1338 (or 1328 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 21232320 is about 4607.8541643589. The cubic root of 21232320 is about 276.9060749296.

Adding to 21232320 its reverse (2323212), we get a palindrome (23555532).

The spelling of 21232320 in words is "twenty-one million, two hundred thirty-two thousand, three hundred twenty".