19985909 has 2 divisors, whose sum is σ = 19985910. Its totient is φ = 19985908.

The previous prime is 19985869. The next prime is 19985923. The reversal of 19985909 is 90958991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19166884 + 819025 = 4378^2 + 905^2 .

It is a cyclic number.

It is not a de Polignac number, because 19985909 - 2²⁴ = 3208693 is a prime.

It is a super-3 number, since 3×19985909³ (a number of 23 digits) contains 333 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19985939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9992954 + 9992955.

It is an arithmetic number, because the mean of its divisors is an integer number (9992955).

Almost surely, 2^19985909 is an apocalyptic number.

It is an amenable number.

19985909 is a deficient number, since it is larger than the sum of its proper divisors (1).

19985909 is an equidigital number, since it uses as much as digits as its factorization.

19985909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 262440, while the sum is 50.

The square root of 19985909 is about 4470.5602557174. The cubic root of 19985909 is about 271.3779985847.

The spelling of 19985909 in words is "nineteen million, nine hundred eighty-five thousand, nine hundred nine".