381209909 has 2 divisors, whose sum is σ = 381209910. Its totient is φ = 381209908.

The previous prime is 381209891. The next prime is 381209947. The reversal of 381209909 is 909902183.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 200307409 + 180902500 = 14153^2 + 13450^2 .

It is an emirp because it is prime and its reverse (909902183) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 381209909 - 2¹⁶ = 381144373 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (381209999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 190604954 + 190604955.

It is an arithmetic number, because the mean of its divisors is an integer number (190604955).

Almost surely, 2^381209909 is an apocalyptic number.

It is an amenable number.

381209909 is a deficient number, since it is larger than the sum of its proper divisors (1).

381209909 is an equidigital number, since it uses as much as digits as its factorization.

381209909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 34992, while the sum is 41.

The square root of 381209909 is about 19524.5975374654. The cubic root of 381209909 is about 725.0835632576.

The spelling of 381209909 in words is "three hundred eighty-one million, two hundred nine thousand, nine hundred nine".