20781020189 has 2 divisors, whose sum is σ = 20781020190. Its totient is φ = 20781020188.

The previous prime is 20781020009. The next prime is 20781020207. The reversal of 20781020189 is 98102018702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17564996089 + 3216024100 = 132533^2 + 56710^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20781020189 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 (20781022189) 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, 10390510094 + 10390510095.

It is an arithmetic number, because the mean of its divisors is an integer number (10390510095).

Almost surely, 2^20781020189 is an apocalyptic number.

It is an amenable number.

20781020189 is a deficient number, since it is larger than the sum of its proper divisors (1).

20781020189 is an equidigital number, since it uses as much as digits as its factorization.

20781020189 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 38.

The spelling of 20781020189 in words is "twenty billion, seven hundred eighty-one million, twenty thousand, one hundred eighty-nine".