209512081 has 2 divisors, whose sum is σ = 209512082. Its totient is φ = 209512080.

The previous prime is 209512073. The next prime is 209512087. The reversal of 209512081 is 180215902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 204490000 + 5022081 = 14300^2 + 2241^2 .

It is a cyclic number.

It is not a de Polignac number, because 209512081 - 2³ = 209512073 is a prime.

It is a super-2 number, since 2×209512081² = 87790624169901122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (209512087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104756040 + 104756041.

It is an arithmetic number, because the mean of its divisors is an integer number (104756041).

Almost surely, 2^209512081 is an apocalyptic number.

It is an amenable number.

209512081 is a deficient number, since it is larger than the sum of its proper divisors (1).

209512081 is an equidigital number, since it uses as much as digits as its factorization.

209512081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 209512081 is about 14474.5321513339. The cubic root of 209512081 is about 593.9314966329.

Adding to 209512081 its reverse (180215902), we get a palindrome (389727983).

It can be divided in two parts, 20951 and 2081, that added together give a palindrome (23032).

The spelling of 209512081 in words is "two hundred nine million, five hundred twelve thousand, eighty-one".