20028209 has 2 divisors, whose sum is σ = 20028210. Its totient is φ = 20028208.

The previous prime is 20028181. The next prime is 20028221. The reversal of 20028209 is 90282002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18879025 + 1149184 = 4345^2 + 1072^2 .

It is a cyclic number.

It is not a de Polignac number, because 20028209 - 2²⁴ = 3250993 is a prime.

It is a super-2 number, since 2×20028209² = 802258311495362, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20028289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10014104 + 10014105.

It is an arithmetic number, because the mean of its divisors is an integer number (10014105).

Almost surely, 2^20028209 is an apocalyptic number.

It is an amenable number.

20028209 is a deficient number, since it is larger than the sum of its proper divisors (1).

20028209 is an equidigital number, since it uses as much as digits as its factorization.

20028209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 20028209 is about 4475.2887057708. The cubic root of 20028209 is about 271.5693200509.

The spelling of 20028209 in words is "twenty million, twenty-eight thousand, two hundred nine".