209390221 has 2 divisors, whose sum is σ = 209390222. Its totient is φ = 209390220.

The previous prime is 209390219. The next prime is 209390249. The reversal of 209390221 is 122093902.

209390221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (209390249) can be obtained adding 209390221 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 188101225 + 21288996 = 13715^2 + 4614^2 .

It is a cyclic number.

It is not a de Polignac number, because 209390221 - 2¹ = 209390219 is a prime.

Together with 209390219, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 209390221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (209396221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104695110 + 104695111.

It is an arithmetic number, because the mean of its divisors is an integer number (104695111).

Almost surely, 2^209390221 is an apocalyptic number.

It is an amenable number.

209390221 is a deficient number, since it is larger than the sum of its proper divisors (1).

209390221 is an equidigital number, since it uses as much as digits as its factorization.

209390221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 209390221 is about 14470.3220765814. The cubic root of 209390221 is about 593.8163234352.

The spelling of 209390221 in words is "two hundred nine million, three hundred ninety thousand, two hundred twenty-one".