21848209 has 2 divisors, whose sum is σ = 21848210. Its totient is φ = 21848208.

The previous prime is 21848147. The next prime is 21848221. The reversal of 21848209 is 90284812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16581184 + 5267025 = 4072^2 + 2295^2 .

It is a cyclic number.

It is not a de Polignac number, because 21848209 - 2¹¹ = 21846161 is a prime.

It is not a weakly prime, because it can be changed into another prime (21848249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10924104 + 10924105.

It is an arithmetic number, because the mean of its divisors is an integer number (10924105).

Almost surely, 2^21848209 is an apocalyptic number.

It is an amenable number.

21848209 is a deficient number, since it is larger than the sum of its proper divisors (1).

21848209 is an equidigital number, since it uses as much as digits as its factorization.

21848209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9216, while the sum is 34.

The square root of 21848209 is about 4674.2067776255. The cubic root of 21848209 is about 279.5580144187.

The spelling of 21848209 in words is "twenty-one million, eight hundred forty-eight thousand, two hundred nine".