19689409 has 4 divisors (see below), whose sum is σ = 19698516. Its totient is φ = 19680304.

The previous prime is 19689401. The next prime is 19689419. The reversal of 19689409 is 90498691.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 90498691 = 19 ⋅4763089.

It can be written as a sum of positive squares in 2 ways, for example, as 7579009 + 12110400 = 2753^2 + 3480^2 .

It is a cyclic number.

It is not a de Polignac number, because 19689409 - 2³ = 19689401 is a prime.

It is a super-3 number, since 3×19689409³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19689401) 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 in 3 ways as a sum of consecutive naturals, for example, 747 + ... + 6319.

It is an arithmetic number, because the mean of its divisors is an integer number (4924629).

Almost surely, 2^19689409 is an apocalyptic number.

It is an amenable number.

19689409 is a deficient number, since it is larger than the sum of its proper divisors (9107).

19689409 is an equidigital number, since it uses as much as digits as its factorization.

19689409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9106.

The product of its (nonzero) digits is 139968, while the sum is 46.

The square root of 19689409 is about 4437.2749520398. The cubic root of 19689409 is about 270.0293018039.

The spelling of 19689409 in words is "nineteen million, six hundred eighty-nine thousand, four hundred nine".