21523589 has 2 divisors, whose sum is σ = 21523590. Its totient is φ = 21523588.

The previous prime is 21523573. The next prime is 21523591. The reversal of 21523589 is 98532512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20775364 + 748225 = 4558^2 + 865^2 .

It is a cyclic number.

It is not a de Polignac number, because 21523589 - 2⁴ = 21523573 is a prime.

Together with 21523591, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21523519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10761794 + 10761795.

It is an arithmetic number, because the mean of its divisors is an integer number (10761795).

Almost surely, 2^21523589 is an apocalyptic number.

It is an amenable number.

21523589 is a deficient number, since it is larger than the sum of its proper divisors (1).

21523589 is an equidigital number, since it uses as much as digits as its factorization.

21523589 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21600, while the sum is 35.

The square root of 21523589 is about 4639.3522177132. The cubic root of 21523589 is about 278.1665453067.

The spelling of 21523589 in words is "twenty-one million, five hundred twenty-three thousand, five hundred eighty-nine".