21608080 has 80 divisors (see below), whose sum is σ = 54996480. Its totient is φ = 7847424.

The previous prime is 21608077. The next prime is 21608089. The reversal of 21608080 is 8080612.

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

21608080 is a modest number, since divided by 8080 gives 2160 as remainder.

It is not an unprimeable number, because it can be changed into a prime (21608089) 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 15 ways as a sum of consecutive naturals, for example, 82029 + ... + 82291.

It is an arithmetic number, because the mean of its divisors is an integer number (687456).

Almost surely, 2^21608080 is an apocalyptic number.

21608080 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 21608080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27498240).

21608080 is an abundant number, since it is smaller than the sum of its proper divisors (33388400).

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

21608080 is a wasteful number, since it uses less digits than its factorization.

21608080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 368 (or 362 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 21608080 is about 4648.4492037668. The cubic root of 21608080 is about 278.5300516485.

Adding to 21608080 its reverse (8080612), we get a palindrome (29688692).

The spelling of 21608080 in words is "twenty-one million, six hundred eight thousand, eighty".