381217909 has 2 divisors, whose sum is σ = 381217910. Its totient is φ = 381217908.

The previous prime is 381217871. The next prime is 381217933. The reversal of 381217909 is 909712183.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 216737284 + 164480625 = 14722^2 + 12825^2 .

It is an emirp because it is prime and its reverse (909712183) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-381217909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (381217999) 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, 190608954 + 190608955.

It is an arithmetic number, because the mean of its divisors is an integer number (190608955).

Almost surely, 2^381217909 is an apocalyptic number.

It is an amenable number.

381217909 is a deficient number, since it is larger than the sum of its proper divisors (1).

381217909 is an equidigital number, since it uses as much as digits as its factorization.

381217909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27216, while the sum is 40.

The square root of 381217909 is about 19524.8024061705. The cubic root of 381217909 is about 725.0886353782.

The spelling of 381217909 in words is "three hundred eighty-one million, two hundred seventeen thousand, nine hundred nine".