199726561 has 4 divisors (see below), whose sum is σ = 200215300. Its totient is φ = 199237824.

The previous prime is 199726559. The next prime is 199726601. The reversal of 199726561 is 165627991.

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 105267600 + 94458961 = 10260^2 + 9719^2 .

It is a cyclic number.

It is not a de Polignac number, because 199726561 - 2¹ = 199726559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199726061) 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 in 3 ways as a sum of consecutive naturals, for example, 243756 + ... + 244573.

It is an arithmetic number, because the mean of its divisors is an integer number (50053825).

Almost surely, 2^199726561 is an apocalyptic number.

It is an amenable number.

199726561 is a deficient number, since it is larger than the sum of its proper divisors (488739).

199726561 is an equidigital number, since it uses as much as digits as its factorization.

199726561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 488738.

The product of its digits is 204120, while the sum is 46.

The square root of 199726561 is about 14132.4647885640. The cubic root of 199726561 is about 584.5369125962.

The spelling of 199726561 in words is "one hundred ninety-nine million, seven hundred twenty-six thousand, five hundred sixty-one".