21905089 has 2 divisors, whose sum is σ = 21905090. Its totient is φ = 21905088.

The previous prime is 21905083. The next prime is 21905099. The reversal of 21905089 is 98050912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17139600 + 4765489 = 4140^2 + 2183^2 .

It is a cyclic number.

It is not a de Polignac number, because 21905089 - 2¹¹ = 21903041 is a prime.

It is not a weakly prime, because it can be changed into another prime (21905083) 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 as a sum of consecutive naturals, namely, 10952544 + 10952545.

It is an arithmetic number, because the mean of its divisors is an integer number (10952545).

Almost surely, 2^21905089 is an apocalyptic number.

It is an amenable number.

21905089 is a deficient number, since it is larger than the sum of its proper divisors (1).

21905089 is an equidigital number, since it uses as much as digits as its factorization.

21905089 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6480, while the sum is 34.

The square root of 21905089 is about 4680.2872775077. The cubic root of 21905089 is about 279.8004062258.

It can be divided in two parts, 2 and 1905089, that added together give a palindrome (1905091).

The spelling of 21905089 in words is "twenty-one million, nine hundred five thousand, eighty-nine".