1165115561 has 2 divisors, whose sum is σ = 1165115562. Its totient is φ = 1165115560.

The previous prime is 1165115557. The next prime is 1165115579. The reversal of 1165115561 is 1655115611.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 722265625 + 442849936 = 26875^2 + 21044^2 .

It is a cyclic number.

It is not a de Polignac number, because 1165115561 - 2² = 1165115557 is a prime.

It is not a weakly prime, because it can be changed into another prime (1165115521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 582557780 + 582557781.

It is an arithmetic number, because the mean of its divisors is an integer number (582557781).

Almost surely, 2^1165115561 is an apocalyptic number.

It is an amenable number.

1165115561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1165115561 is an equidigital number, since it uses as much as digits as its factorization.

1165115561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4500, while the sum is 32.

The square root of 1165115561 is about 34133.7891392093. The cubic root of 1165115561 is about 1052.2598526431.

The spelling of 1165115561 in words is "one billion, one hundred sixty-five million, one hundred fifteen thousand, five hundred sixty-one".