21243589 has 2 divisors, whose sum is σ = 21243590. Its totient is φ = 21243588.

The previous prime is 21243581. The next prime is 21243611. The reversal of 21243589 is 98534212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17850625 + 3392964 = 4225^2 + 1842^2 .

It is a cyclic number.

It is not a de Polignac number, because 21243589 - 2³ = 21243581 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21243581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621794 + 10621795.

It is an arithmetic number, because the mean of its divisors is an integer number (10621795).

Almost surely, 2^21243589 is an apocalyptic number.

It is an amenable number.

21243589 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243589 is an equidigital number, since it uses as much as digits as its factorization.

21243589 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 34.

The square root of 21243589 is about 4609.0768056087. The cubic root of 21243589 is about 276.9550553309.

The spelling of 21243589 in words is "twenty-one million, two hundred forty-three thousand, five hundred eighty-nine".