21216008 has 32 divisors (see below), whose sum is σ = 45684000. Its totient is φ = 9135360.

The previous prime is 21216001. The next prime is 21216011. The reversal of 21216008 is 80061212.

It is not an unprimeable number, because it can be changed into a prime (21216001) 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 7 ways as a sum of consecutive naturals, for example, 4673 + ... + 8016.

It is an arithmetic number, because the mean of its divisors is an integer number (1427625).

Almost surely, 2^21216008 is an apocalyptic number.

It is an amenable number.

21216008 is an abundant number, since it is smaller than the sum of its proper divisors (24467992).

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

21216008 is a wasteful number, since it uses less digits than its factorization.

21216008 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12725 (or 12721 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21216008 is about 4606.0838029719. The cubic root of 21216008 is about 276.8351445569.

The spelling of 21216008 in words is "twenty-one million, two hundred sixteen thousand, eight".