20840380409 has 2 divisors, whose sum is σ = 20840380410. Its totient is φ = 20840380408.

The previous prime is 20840380333. The next prime is 20840380411. The reversal of 20840380409 is 90408304802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20751266809 + 89113600 = 144053^2 + 9440^2 .

It is a cyclic number.

It is not a de Polignac number, because 20840380409 - 2³² = 16545413113 is a prime.

Together with 20840380411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20840380909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10420190204 + 10420190205.

It is an arithmetic number, because the mean of its divisors is an integer number (10420190205).

Almost surely, 2^20840380409 is an apocalyptic number.

It is an amenable number.

20840380409 is a deficient number, since it is larger than the sum of its proper divisors (1).

20840380409 is an equidigital number, since it uses as much as digits as its factorization.

20840380409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 55296, while the sum is 38.

The spelling of 20840380409 in words is "twenty billion, eight hundred forty million, three hundred eighty thousand, four hundred nine".