11561661309 has 16 divisors (see below), whose sum is σ = 17134265664. Its totient is φ = 6874857600.

The previous prime is 11561661259. The next prime is 11561661311. The reversal of 11561661309 is 90316616511.

It is not a de Polignac number, because 11561661309 - 2¹² = 11561657213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11561661809) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3303472 + ... + 3306969.

It is an arithmetic number, because the mean of its divisors is an integer number (1070891604).

Almost surely, 2^11561661309 is an apocalyptic number.

It is an amenable number.

11561661309 is a deficient number, since it is larger than the sum of its proper divisors (5572604355).

11561661309 is a wasteful number, since it uses less digits than its factorization.

11561661309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6610508.

The product of its (nonzero) digits is 29160, while the sum is 39.

The spelling of 11561661309 in words is "eleven billion, five hundred sixty-one million, six hundred sixty-one thousand, three hundred nine".