21564160 has 72 divisors (see below), whose sum is σ = 54746496. Its totient is φ = 8110080.

The previous prime is 21564149. The next prime is 21564181. The reversal of 21564160 is 6146512.

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, 21265 + ... + 22255.

It is an arithmetic number, because the mean of its divisors is an integer number (760368).

Almost surely, 2^21564160 is an apocalyptic number.

21564160 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 21564160, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27373248).

21564160 is an abundant number, since it is smaller than the sum of its proper divisors (33182336).

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

21564160 is an equidigital number, since it uses as much as digits as its factorization.

21564160 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1029 (or 1015 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21564160 is about 4643.7226446031. The cubic root of 21564160 is about 278.3412127602.

The spelling of 21564160 in words is "twenty-one million, five hundred sixty-four thousand, one hundred sixty".