199961009 has 4 divisors (see below), whose sum is σ = 201234804. Its totient is φ = 198687216.

The previous prime is 199960993. The next prime is 199961033. The reversal of 199961009 is 900169991.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19998784 + 179962225 = 4472^2 + 13415^2 .

It is a cyclic number.

It is not a de Polignac number, because 199961009 - 2⁴ = 199960993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199961039) 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, 636662 + ... + 636975.

It is an arithmetic number, because the mean of its divisors is an integer number (50308701).

Almost surely, 2^199961009 is an apocalyptic number.

It is an amenable number.

199961009 is a deficient number, since it is larger than the sum of its proper divisors (1273795).

199961009 is a wasteful number, since it uses less digits than its factorization.

199961009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1273794.

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

The square root of 199961009 is about 14140.7570165108. The cubic root of 199961009 is about 584.7655417141.

The spelling of 199961009 in words is "one hundred ninety-nine million, nine hundred sixty-one thousand, nine".