21280608 has 72 divisors (see below), whose sum is σ = 63718200. Its totient is φ = 6718464.

The previous prime is 21280579. The next prime is 21280639. The reversal of 21280608 is 80608212.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 3528 + ... + 7416.

It is an arithmetic number, because the mean of its divisors is an integer number (884975).

Almost surely, 2^21280608 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21280608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31859100).

21280608 is an abundant number, since it is smaller than the sum of its proper divisors (42437592).

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

21280608 is a wasteful number, since it uses less digits than its factorization.

21280608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3924 (or 3913 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21280608 is about 4613.0909377553. The cubic root of 21280608 is about 277.1158355953.

The spelling of 21280608 in words is "twenty-one million, two hundred eighty thousand, six hundred eight".