21452209 has 2 divisors, whose sum is σ = 21452210. Its totient is φ = 21452208.

The previous prime is 21452203. The next prime is 21452219. The reversal of 21452209 is 90225412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11390625 + 10061584 = 3375^2 + 3172^2 .

It is a cyclic number.

It is not a de Polignac number, because 21452209 - 2³ = 21452201 is a prime.

It is not a weakly prime, because it can be changed into another prime (21452201) 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, 10726104 + 10726105.

It is an arithmetic number, because the mean of its divisors is an integer number (10726105).

Almost surely, 2^21452209 is an apocalyptic number.

It is an amenable number.

21452209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21452209 is an equidigital number, since it uses as much as digits as its factorization.

21452209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21452209 is about 4631.6529446840. The cubic root of 21452209 is about 277.8587044860.

The spelling of 21452209 in words is "twenty-one million, four hundred fifty-two thousand, two hundred nine".