21332320 has 24 divisors (see below), whose sum is σ = 50397984. Its totient is φ = 8532864.

The previous prime is 21332261. The next prime is 21332329. The reversal of 21332320 is 2323312.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a junction number, because it is equal to n+sod(n) for n = 21332294 and 21332303.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21332329) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66504 + ... + 66823.

It is an arithmetic number, because the mean of its divisors is an integer number (2099916).

Almost surely, 2^21332320 is an apocalyptic number.

21332320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21332320 is an abundant number, since it is smaller than the sum of its proper divisors (29065664).

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

21332320 is a wasteful number, since it uses less digits than its factorization.

21332320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133342 (or 133334 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 16.

The square root of 21332320 is about 4618.6924556632. The cubic root of 21332320 is about 277.3401183827.

Adding to 21332320 its reverse (2323312), we get a palindrome (23655632).

The spelling of 21332320 in words is "twenty-one million, three hundred thirty-two thousand, three hundred twenty".