19709909 has 2 divisors, whose sum is σ = 19709910. Its totient is φ = 19709908.

The previous prime is 19709903. The next prime is 19709939. The reversal of 19709909 is 90990791.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18679684 + 1030225 = 4322^2 + 1015^2 .

It is a cyclic number.

It is not a de Polignac number, because 19709909 - 2²⁰ = 18661333 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19709909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19709903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9854954 + 9854955.

It is an arithmetic number, because the mean of its divisors is an integer number (9854955).

Almost surely, 2^19709909 is an apocalyptic number.

It is an amenable number.

19709909 is a deficient number, since it is larger than the sum of its proper divisors (1).

19709909 is an equidigital number, since it uses as much as digits as its factorization.

19709909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 45927, while the sum is 44.

The square root of 19709909 is about 4439.5843273892. The cubic root of 19709909 is about 270.1229846671.

The spelling of 19709909 in words is "nineteen million, seven hundred nine thousand, nine hundred nine".