21323320 has 32 divisors (see below), whose sum is σ = 50504400. Its totient is φ = 8080128.

The previous prime is 21323311. The next prime is 21323371. The reversal of 21323320 is 2332312.

It is a zygodrome in base 9.

It is a junction number, because it is equal to n+sod(n) for n = 21323294 and 21323303.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13269 + ... + 14788.

Almost surely, 2^21323320 is an apocalyptic number.

21323320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21323320 is an abundant number, since it is smaller than the sum of its proper divisors (29181080).

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

21323320 is a wasteful number, since it uses less digits than its factorization.

21323320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28087 (or 28083 counting only the distinct ones).

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

The square root of 21323320 is about 4617.7180511590. The cubic root of 21323320 is about 277.3011100896.

Adding to 21323320 its reverse (2332312), we get a palindrome (23655632).

It can be divided in two parts, 213233 and 20, that multiplied together give a triangular number (4264660 = T₂₉₂₀).

The spelling of 21323320 in words is "twenty-one million, three hundred twenty-three thousand, three hundred twenty".