19989509 has 8 divisors (see below), whose sum is σ = 21032088. Its totient is φ = 18973440.

The previous prime is 19989503. The next prime is 19989511. The reversal of 19989509 is 90598991.

It can be written as a sum of positive squares in 4 ways, for example, as 3204100 + 16785409 = 1790^2 + 4097^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19989509 - 2⁴ = 19989493 is a prime.

It is a super-2 number, since 2×19989509² = 799160940122162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19989503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5072 + ... + 8105.

It is an arithmetic number, because the mean of its divisors is an integer number (2629011).

Almost surely, 2^19989509 is an apocalyptic number.

It is an amenable number.

19989509 is a deficient number, since it is larger than the sum of its proper divisors (1042579).

19989509 is a wasteful number, since it uses less digits than its factorization.

19989509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13255.

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

The square root of 19989509 is about 4470.9628716866. The cubic root of 19989509 is about 271.3942917664.

The spelling of 19989509 in words is "nineteen million, nine hundred eighty-nine thousand, five hundred nine".