20399636909 has 2 divisors, whose sum is σ = 20399636910. Its totient is φ = 20399636908.

The previous prime is 20399636849. The next prime is 20399636911. The reversal of 20399636909 is 90963699302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16946311684 + 3453325225 = 130178^2 + 58765^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20399636909 is a prime.

It is a super-2 number, since 2×20399636909² (a number of 21 digits) contains 22 as substring.

Together with 20399636911, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20399632909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10199818454 + 10199818455.

It is an arithmetic number, because the mean of its divisors is an integer number (10199818455).

Almost surely, 2^20399636909 is an apocalyptic number.

It is an amenable number.

20399636909 is a deficient number, since it is larger than the sum of its proper divisors (1).

20399636909 is an equidigital number, since it uses as much as digits as its factorization.

20399636909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4251528, while the sum is 56.

The spelling of 20399636909 in words is "twenty billion, three hundred ninety-nine million, six hundred thirty-six thousand, nine hundred nine".