21316689 has 33 divisors (see below), whose sum is σ = 33746313. Its totient is φ = 13463172.

The previous prime is 21316667. The next prime is 21316693. The reversal of 21316689 is 98661312.

The square root of 21316689 is 4617.

It is a perfect power (a square), and thus also a powerful number.

21316689 is nontrivially palindromic in base 8.

It is not a de Polignac number, because 21316689 - 2⁹ = 21316177 is a prime.

It is a Curzon number.

It is a nialpdrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (21316609) by changing a digit.

It is a polite number, since it can be written in 32 ways as a sum of consecutive naturals, for example, 1121922 + ... + 1121940.

Almost surely, 2^21316689 is an apocalyptic number.

21316689 is the 4617-th square number.

21316689 is the 2309-th centered octagonal number.

It is an amenable number.

21316689 is a deficient number, since it is larger than the sum of its proper divisors (12429624).

21316689 is an frugal number, since it uses more digits than its factorization.

21316689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68 (or 22 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The cubic root of 21316689 is about 277.2723626228.

Multiplying 21316689 by its sum of digits (36), we get a square (767400804 = 27702²).

The spelling of 21316689 in words is "twenty-one million, three hundred sixteen thousand, six hundred eighty-nine".