21168130909 has 2 divisors, whose sum is σ = 21168130910. Its totient is φ = 21168130908.

The previous prime is 21168130901. The next prime is 21168130931. The reversal of 21168130909 is 90903186112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20787295684 + 380835225 = 144178^2 + 19515^2 .

It is a cyclic number.

It is not a de Polignac number, because 21168130909 - 2³ = 21168130901 is a prime.

It is a super-2 number, since 2×21168130909² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21168130901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10584065454 + 10584065455.

It is an arithmetic number, because the mean of its divisors is an integer number (10584065455).

Almost surely, 2^21168130909 is an apocalyptic number.

It is an amenable number.

21168130909 is a deficient number, since it is larger than the sum of its proper divisors (1).

21168130909 is an equidigital number, since it uses as much as digits as its factorization.

21168130909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23328, while the sum is 40.

The spelling of 21168130909 in words is "twenty-one billion, one hundred sixty-eight million, one hundred thirty thousand, nine hundred nine".