19919609 has 2 divisors, whose sum is σ = 19919610. Its totient is φ = 19919608.

The previous prime is 19919591. The next prime is 19919617. The reversal of 19919609 is 90691991.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17808400 + 2111209 = 4220^2 + 1453^2 .

It is a cyclic number.

It is not a de Polignac number, because 19919609 - 2²⁴ = 3142393 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19919609.

It is not a weakly prime, because it can be changed into another prime (19919309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9959804 + 9959805.

It is an arithmetic number, because the mean of its divisors is an integer number (9959805).

Almost surely, 2^19919609 is an apocalyptic number.

It is an amenable number.

19919609 is a deficient number, since it is larger than the sum of its proper divisors (1).

19919609 is an equidigital number, since it uses as much as digits as its factorization.

19919609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 39366, while the sum is 44.

The square root of 19919609 is about 4463.1389178469. The cubic root of 19919609 is about 271.0775820323.

The spelling of 19919609 in words is "nineteen million, nine hundred nineteen thousand, six hundred nine".