1205120309 has 2 divisors, whose sum is σ = 1205120310. Its totient is φ = 1205120308.

The previous prime is 1205120297. The next prime is 1205120333. The reversal of 1205120309 is 9030215021.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 874680625 + 330439684 = 29575^2 + 18178^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1205120309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1205120359) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 602560154 + 602560155.

It is an arithmetic number, because the mean of its divisors is an integer number (602560155).

Almost surely, 2^1205120309 is an apocalyptic number.

It is an amenable number.

1205120309 is a deficient number, since it is larger than the sum of its proper divisors (1).

1205120309 is an equidigital number, since it uses as much as digits as its factorization.

1205120309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 1205120309 is about 34714.8427765416. The cubic root of 1205120309 is about 1064.1678523913.

The spelling of 1205120309 in words is "one billion, two hundred five million, one hundred twenty thousand, three hundred nine".