21716321 has 8 divisors (see below), whose sum is σ = 23757600. Its totient is φ = 19686240.

The previous prime is 21716311. The next prime is 21716323. The reversal of 21716321 is 12361712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21716321 - 2¹⁰ = 21715297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21716323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1565 + ... + 6773.

It is an arithmetic number, because the mean of its divisors is an integer number (2969700).

Almost surely, 2^21716321 is an apocalyptic number.

It is an amenable number.

21716321 is a deficient number, since it is larger than the sum of its proper divisors (2041279).

21716321 is a wasteful number, since it uses less digits than its factorization.

21716321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5599.

The product of its digits is 504, while the sum is 23.

The square root of 21716321 is about 4660.0773598729. The cubic root of 21716321 is about 278.9943559021.

The spelling of 21716321 in words is "twenty-one million, seven hundred sixteen thousand, three hundred twenty-one".