21384938189 has 2 divisors, whose sum is σ = 21384938190. Its totient is φ = 21384938188.

The previous prime is 21384938123. The next prime is 21384938213. The reversal of 21384938189 is 98183948312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20440420900 + 944517289 = 142970^2 + 30733^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21384938189 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 (21384938089) 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, 10692469094 + 10692469095.

It is an arithmetic number, because the mean of its divisors is an integer number (10692469095).

Almost surely, 2^21384938189 is an apocalyptic number.

It is an amenable number.

21384938189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21384938189 is an equidigital number, since it uses as much as digits as its factorization.

21384938189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2985984, while the sum is 56.

The spelling of 21384938189 in words is "twenty-one billion, three hundred eighty-four million, nine hundred thirty-eight thousand, one hundred eighty-nine".