209670221 has 2 divisors, whose sum is σ = 209670222. Its totient is φ = 209670220.

The previous prime is 209670217. The next prime is 209670233. The reversal of 209670221 is 122076902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199204996 + 10465225 = 14114^2 + 3235^2 .

It is a cyclic number.

It is not a de Polignac number, because 209670221 - 2² = 209670217 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209670281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104835110 + 104835111.

It is an arithmetic number, because the mean of its divisors is an integer number (104835111).

Almost surely, 2^209670221 is an apocalyptic number.

It is an amenable number.

209670221 is a deficient number, since it is larger than the sum of its proper divisors (1).

209670221 is an equidigital number, since it uses as much as digits as its factorization.

209670221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 29.

The square root of 209670221 is about 14479.9938190595. The cubic root of 209670221 is about 594.0808924815.

The spelling of 209670221 in words is "two hundred nine million, six hundred seventy thousand, two hundred twenty-one".