209481121 has 2 divisors, whose sum is σ = 209481122. Its totient is φ = 209481120.

The previous prime is 209481119. The next prime is 209481179. The reversal of 209481121 is 121184902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 205635600 + 3845521 = 14340^2 + 1961^2 .

It is a cyclic number.

It is not a de Polignac number, because 209481121 - 2¹ = 209481119 is a prime.

Together with 209481119, 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 209481121.

It is not a weakly prime, because it can be changed into another prime (209481221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104740560 + 104740561.

It is an arithmetic number, because the mean of its divisors is an integer number (104740561).

Almost surely, 2^209481121 is an apocalyptic number.

It is an amenable number.

209481121 is a deficient number, since it is larger than the sum of its proper divisors (1).

209481121 is an equidigital number, since it uses as much as digits as its factorization.

209481121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 209481121 is about 14473.4626472037. The cubic root of 209481121 is about 593.9022397282.

The spelling of 209481121 in words is "two hundred nine million, four hundred eighty-one thousand, one hundred twenty-one".