21360864 has 144 divisors (see below), whose sum is σ = 68947200. Its totient is φ = 5757696.

The previous prime is 21360863. The next prime is 21360881. The reversal of 21360864 is 46806312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21360863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 89257 + ... + 89495.

It is an arithmetic number, because the mean of its divisors is an integer number (478800).

Almost surely, 2^21360864 is an apocalyptic number.

21360864 is a gapful number since it is divisible by the number (24) 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 21360864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34473600).

21360864 is an abundant number, since it is smaller than the sum of its proper divisors (47586336).

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

21360864 is a wasteful number, since it uses less digits than its factorization.

21360864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285 (or 270 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 21360864 is about 4621.7814747130. The cubic root of 21360864 is about 277.4637628195.

The spelling of 21360864 in words is "twenty-one million, three hundred sixty thousand, eight hundred sixty-four".