209021 has 2 divisors, whose sum is σ = 209022. Its totient is φ = 209020.

The previous prime is 208997. The next prime is 209029. The reversal of 209021 is 120902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 148996 + 60025 = 386^2 + 245^2 .

It is a cyclic number.

It is not a de Polignac number, because 209021 - 2¹⁰ = 207997 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 208987 and 209005.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104510 + 104511.

It is an arithmetic number, because the mean of its divisors is an integer number (104511).

2²⁰⁹⁰²¹ is an apocalyptic number.

It is an amenable number.

209021 is a deficient number, since it is larger than the sum of its proper divisors (1).

209021 is an equidigital number, since it uses as much as digits as its factorization.

209021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 209021 is about 457.1881450782. The cubic root of 209021 is about 59.3467089597.

Adding to 209021 its reverse (120902), we get a palindrome (329923).

The spelling of 209021 in words is "two hundred nine thousand, twenty-one".