21644089 has 2 divisors, whose sum is σ = 21644090. Its totient is φ = 21644088.

The previous prime is 21644053. The next prime is 21644099. The reversal of 21644089 is 98044612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19954089 + 1690000 = 4467^2 + 1300^2 .

It is a cyclic number.

It is not a de Polignac number, because 21644089 - 2⁷ = 21643961 is a prime.

It is not a weakly prime, because it can be changed into another prime (21644039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10822044 + 10822045.

It is an arithmetic number, because the mean of its divisors is an integer number (10822045).

Almost surely, 2^21644089 is an apocalyptic number.

It is an amenable number.

21644089 is a deficient number, since it is larger than the sum of its proper divisors (1).

21644089 is an equidigital number, since it uses as much as digits as its factorization.

21644089 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 21644089 is about 4652.3208186882. The cubic root of 21644089 is about 278.6846855090.

The spelling of 21644089 in words is "twenty-one million, six hundred forty-four thousand, eighty-nine".