21216608 has 48 divisors (see below), whose sum is σ = 48736800. Its totient is φ = 9088128.

The previous prime is 21216607. The next prime is 21216619. The reversal of 21216608 is 80661212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21216607) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10010 + ... + 11942.

It is an arithmetic number, because the mean of its divisors is an integer number (1015350).

Almost surely, 2^21216608 is an apocalyptic number.

21216608 is a gapful number since it is divisible by the number (28) 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 21216608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24368400).

21216608 is an abundant number, since it is smaller than the sum of its proper divisors (27520192).

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

21216608 is an equidigital number, since it uses as much as digits as its factorization.

21216608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1964 (or 1942 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21216608 is about 4606.1489337623. The cubic root of 21216608 is about 276.8377542141.

The spelling of 21216608 in words is "twenty-one million, two hundred sixteen thousand, six hundred eight".