1161365561 has 2 divisors, whose sum is σ = 1161365562. Its totient is φ = 1161365560.

The previous prime is 1161365551. The next prime is 1161365563. The reversal of 1161365561 is 1655631611.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1110955561 + 50410000 = 33331^2 + 7100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1161365561 is a prime.

It is a Sophie Germain prime.

Together with 1161365563, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1161365563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 580682780 + 580682781.

It is an arithmetic number, because the mean of its divisors is an integer number (580682781).

Almost surely, 2^1161365561 is an apocalyptic number.

It is an amenable number.

1161365561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1161365561 is an equidigital number, since it uses as much as digits as its factorization.

1161365561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16200, while the sum is 35.

The square root of 1161365561 is about 34078.8139611695. The cubic root of 1161365561 is about 1051.1297171086.

The spelling of 1161365561 in words is "one billion, one hundred sixty-one million, three hundred sixty-five thousand, five hundred sixty-one".