211240409 has 2 divisors, whose sum is σ = 211240410. Its totient is φ = 211240408.

The previous prime is 211240399. The next prime is 211240411. The reversal of 211240409 is 904042112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 209670400 + 1570009 = 14480^2 + 1253^2 .

It is a cyclic number.

It is not a de Polignac number, because 211240409 - 2⁸ = 211240153 is a prime.

It is a Sophie Germain prime.

Together with 211240411, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (211240459) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105620204 + 105620205.

It is an arithmetic number, because the mean of its divisors is an integer number (105620205).

Almost surely, 2^211240409 is an apocalyptic number.

It is an amenable number.

211240409 is a deficient number, since it is larger than the sum of its proper divisors (1).

211240409 is an equidigital number, since it uses as much as digits as its factorization.

211240409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 211240409 is about 14534.1119095733. Note that the first 3 decimals coincide. The cubic root of 211240409 is about 595.5601992795.

The spelling of 211240409 in words is "two hundred eleven million, two hundred forty thousand, four hundred nine".