19908809 has 2 divisors, whose sum is σ = 19908810. Its totient is φ = 19908808.

The previous prime is 19908803. The next prime is 19908839. The reversal of 19908809 is 90880991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18731584 + 1177225 = 4328^2 + 1085^2 .

It is a cyclic number.

It is not a de Polignac number, because 19908809 - 2¹² = 19904713 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 19908809.

It is not a weakly prime, because it can be changed into another prime (19908803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9954404 + 9954405.

It is an arithmetic number, because the mean of its divisors is an integer number (9954405).

Almost surely, 2^19908809 is an apocalyptic number.

It is an amenable number.

19908809 is a deficient number, since it is larger than the sum of its proper divisors (1).

19908809 is an equidigital number, since it uses as much as digits as its factorization.

19908809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46656, while the sum is 44.

The square root of 19908809 is about 4461.9288430005. The cubic root of 19908809 is about 271.0285822896.

The spelling of 19908809 in words is "nineteen million, nine hundred eight thousand, eight hundred nine".