21566080 has 64 divisors (see below), whose sum is σ = 53268480. Its totient is φ = 8340480.

The previous prime is 21566063. The next prime is 21566087. The reversal of 21566080 is 8066512.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (21566087) by changing a digit.

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, 19297 + ... + 20383.

It is an arithmetic number, because the mean of its divisors is an integer number (832320).

Almost surely, 2^21566080 is an apocalyptic number.

21566080 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 21566080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26634240).

21566080 is an abundant number, since it is smaller than the sum of its proper divisors (31702400).

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

21566080 is a wasteful number, since it uses less digits than its factorization.

21566080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1137 (or 1125 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 28.

The square root of 21566080 is about 4643.9293706946. The cubic root of 21566080 is about 278.3494733689.

The spelling of 21566080 in words is "twenty-one million, five hundred sixty-six thousand, eighty".