215205409 has 2 divisors, whose sum is σ = 215205410. Its totient is φ = 215205408.

The previous prime is 215205383. The next prime is 215205427. The reversal of 215205409 is 904502512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 145733184 + 69472225 = 12072^2 + 8335^2 .

It is a cyclic number.

It is not a de Polignac number, because 215205409 - 2¹¹ = 215203361 is a prime.

It is not a weakly prime, because it can be changed into another prime (215205439) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107602704 + 107602705.

It is an arithmetic number, because the mean of its divisors is an integer number (107602705).

Almost surely, 2^215205409 is an apocalyptic number.

It is an amenable number.

215205409 is a deficient number, since it is larger than the sum of its proper divisors (1).

215205409 is an equidigital number, since it uses as much as digits as its factorization.

215205409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 215205409 is about 14669.8810151957. The cubic root of 215205409 is about 599.2633635740.

The spelling of 215205409 in words is "two hundred fifteen million, two hundred five thousand, four hundred nine".