1161001561 has 2 divisors, whose sum is σ = 1161001562. Its totient is φ = 1161001560.

The previous prime is 1161001559. The next prime is 1161001571. The reversal of 1161001561 is 1651001611.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 710755600 + 450245961 = 26660^2 + 21219^2 .

It is a cyclic number.

It is not a de Polignac number, because 1161001561 - 2¹ = 1161001559 is a prime.

Together with 1161001559, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1161001571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 580500780 + 580500781.

It is an arithmetic number, because the mean of its divisors is an integer number (580500781).

Almost surely, 2^1161001561 is an apocalyptic number.

It is an amenable number.

1161001561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1161001561 is an equidigital number, since it uses as much as digits as its factorization.

1161001561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 180, while the sum is 22.

The square root of 1161001561 is about 34073.4729811917. The cubic root of 1161001561 is about 1051.0198891584.

The spelling of 1161001561 in words is "one billion, one hundred sixty-one million, one thousand, five hundred sixty-one".