21368320 has 80 divisors (see below), whose sum is σ = 54358128. Its totient is φ = 8028160.

The previous prime is 21368309. The next prime is 21368353. The reversal of 21368320 is 2386312.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43275 + ... + 43765.

Almost surely, 2^21368320 is an apocalyptic number.

21368320 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 21368320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27179064).

21368320 is an abundant number, since it is smaller than the sum of its proper divisors (32989808).

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

21368320 is an equidigital number, since it uses as much as digits as its factorization.

21368320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 531 (or 515 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21368320 is about 4622.5880197136. The cubic root of 21368320 is about 277.4960419315.

The spelling of 21368320 in words is "twenty-one million, three hundred sixty-eight thousand, three hundred twenty".