11511165561 has 16 divisors (see below), whose sum is σ = 18464025600. Its totient is φ = 6231608208.

The previous prime is 11511165541. The next prime is 11511165581. The reversal of 11511165561 is 16556111511.

It is an interprime number because it is at equal distance from previous prime (11511165541) and next prime (11511165581).

It is not a de Polignac number, because 11511165561 - 2⁵ = 11511165529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (11511165521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14424621 + ... + 14425418.

It is an arithmetic number, because the mean of its divisors is an integer number (1154001600).

Almost surely, 2^11511165561 is an apocalyptic number.

It is an amenable number.

11511165561 is a deficient number, since it is larger than the sum of its proper divisors (6952860039).

11511165561 is a wasteful number, since it uses less digits than its factorization.

11511165561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28850068.

The product of its digits is 4500, while the sum is 33.

The spelling of 11511165561 in words is "eleven billion, five hundred eleven million, one hundred sixty-five thousand, five hundred sixty-one".