195561661 has 4 divisors (see below), whose sum is σ = 205854400. Its totient is φ = 185268924.

The previous prime is 195561643. The next prime is 195561673. The reversal of 195561661 is 166165591.

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.

It is not a de Polignac number, because 195561661 - 2⁵ = 195561629 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 (195591661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5146341 + ... + 5146378.

It is an arithmetic number, because the mean of its divisors is an integer number (51463600).

Almost surely, 2^195561661 is an apocalyptic number.

It is an amenable number.

195561661 is a deficient number, since it is larger than the sum of its proper divisors (10292739).

195561661 is a wasteful number, since it uses less digits than its factorization.

195561661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10292738.

The product of its digits is 48600, while the sum is 40.

The square root of 195561661 is about 13984.3362731307. The cubic root of 195561661 is about 580.4452199836.

The spelling of 195561661 in words is "one hundred ninety-five million, five hundred sixty-one thousand, six hundred sixty-one".