21123589 has 2 divisors, whose sum is σ = 21123590. Its totient is φ = 21123588.

The previous prime is 21123533. The next prime is 21123607. The reversal of 21123589 is 98532112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15444900 + 5678689 = 3930^2 + 2383^2 .

It is a cyclic number.

It is not a de Polignac number, because 21123589 - 2⁷ = 21123461 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21123589.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21123689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561794 + 10561795.

It is an arithmetic number, because the mean of its divisors is an integer number (10561795).

Almost surely, 2^21123589 is an apocalyptic number.

It is an amenable number.

21123589 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123589 is an equidigital number, since it uses as much as digits as its factorization.

21123589 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4320, while the sum is 31.

The square root of 21123589 is about 4596.0405785850. The cubic root of 21123589 is about 276.4325858319.

It can be divided in two parts, 21123 and 589, that added together give a palindrome (21712).

The spelling of 21123589 in words is "twenty-one million, one hundred twenty-three thousand, five hundred eighty-nine".