20381909 has 2 divisors, whose sum is σ = 20381910. Its totient is φ = 20381908.

The previous prime is 20381891. The next prime is 20381939. The reversal of 20381909 is 90918302.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13118884 + 7263025 = 3622^2 + 2695^2 .

It is a cyclic number.

It is not a de Polignac number, because 20381909 - 2⁸ = 20381653 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20381939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10190954 + 10190955.

It is an arithmetic number, because the mean of its divisors is an integer number (10190955).

Almost surely, 2^20381909 is an apocalyptic number.

It is an amenable number.

20381909 is a deficient number, since it is larger than the sum of its proper divisors (1).

20381909 is an equidigital number, since it uses as much as digits as its factorization.

20381909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 20381909 is about 4514.6327646886. The cubic root of 20381909 is about 273.1586468924.

The spelling of 20381909 in words is "twenty million, three hundred eighty-one thousand, nine hundred nine".