199997509 has 4 divisors (see below), whose sum is σ = 201436480. Its totient is φ = 198558540.

The previous prime is 199997491. The next prime is 199997513. The reversal of 199997509 is 905799991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 905799991 = 11939 ⋅75869.

It is a cyclic number.

It is not a de Polignac number, because 199997509 - 2⁹ = 199996997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199997599) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 719277 + ... + 719554.

It is an arithmetic number, because the mean of its divisors is an integer number (50359120).

Almost surely, 2^199997509 is an apocalyptic number.

It is an amenable number.

199997509 is a deficient number, since it is larger than the sum of its proper divisors (1438971).

199997509 is a wasteful number, since it uses less digits than its factorization.

199997509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1438970.

The product of its (nonzero) digits is 2066715, while the sum is 58.

The square root of 199997509 is about 14142.0475533071. The cubic root of 199997509 is about 584.8011197231.

The spelling of 199997509 in words is "one hundred ninety-nine million, nine hundred ninety-seven thousand, five hundred nine".