21306589 has 6 divisors (see below), whose sum is σ = 21519134. Its totient is φ = 21096120.

The previous prime is 21306587. The next prime is 21306617. The reversal of 21306589 is 98560312.

It can be written as a sum of positive squares in only one way, i.e., 11002489 + 10304100 = 3317^2 + 3210^2 .

It is not a de Polignac number, because 21306589 - 2¹ = 21306587 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21306587) 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 5 ways as a sum of consecutive naturals, for example, 10519 + ... + 12379.

Almost surely, 2^21306589 is an apocalyptic number.

It is an amenable number.

21306589 is a deficient number, since it is larger than the sum of its proper divisors (212545).

21306589 is an equidigital number, since it uses as much as digits as its factorization.

21306589 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2075 (or 1968 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 21306589 is about 4615.9060865663. The cubic root of 21306589 is about 277.2285644940.

The spelling of 21306589 in words is "twenty-one million, three hundred six thousand, five hundred eighty-nine".