199706561 has 4 divisors (see below), whose sum is σ = 199824324. Its totient is φ = 199588800.

The previous prime is 199706543. The next prime is 199706567. The reversal of 199706561 is 165607991.

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 178730161 + 20976400 = 13369^2 + 4580^2 .

It is a cyclic number.

It is not a de Polignac number, because 199706561 - 2¹⁸ = 199444417 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (199706567) 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, 56300 + ... + 59741.

It is an arithmetic number, because the mean of its divisors is an integer number (49956081).

Almost surely, 2^199706561 is an apocalyptic number.

It is an amenable number.

199706561 is a deficient number, since it is larger than the sum of its proper divisors (117763).

199706561 is a wasteful number, since it uses less digits than its factorization.

199706561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117762.

The product of its (nonzero) digits is 102060, while the sum is 44.

The square root of 199706561 is about 14131.7571801952. The cubic root of 199706561 is about 584.5174007054.

The spelling of 199706561 in words is "one hundred ninety-nine million, seven hundred six thousand, five hundred sixty-one".