193661561 has 4 divisors (see below), whose sum is σ = 193826724. Its totient is φ = 193496400.

The previous prime is 193661549. The next prime is 193661591. The reversal of 193661561 is 165166391.

It is a happy number.

193661561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 161671225 + 31990336 = 12715^2 + 5656^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-193661561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (193661591) 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, 80810 + ... + 83171.

It is an arithmetic number, because the mean of its divisors is an integer number (48456681).

Almost surely, 2^193661561 is an apocalyptic number.

It is an amenable number.

193661561 is a deficient number, since it is larger than the sum of its proper divisors (165163).

193661561 is a wasteful number, since it uses less digits than its factorization.

193661561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165162.

The product of its digits is 29160, while the sum is 38.

The square root of 193661561 is about 13916.2337218085. The cubic root of 193661561 is about 578.5592072465.

The spelling of 193661561 in words is "one hundred ninety-three million, six hundred sixty-one thousand, five hundred sixty-one".