11661501610561 has 8 divisors (see below), whose sum is σ = 12834218990304. Its totient is φ = 10507547709120.

The previous prime is 11661501610513. The next prime is 11661501610571. The reversal of 11661501610561 is 16501610516611.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 11661501610561 - 2²⁵ = 11661468056129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11661501610501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4690868271 + ... + 4690870756.

It is an arithmetic number, because the mean of its divisors is an integer number (1604277373788).

Almost surely, 2^{11661501610561} is an apocalyptic number.

11661501610561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

11661501610561 is a deficient number, since it is larger than the sum of its proper divisors (1172717379743).

11661501610561 is a wasteful number, since it uses less digits than its factorization.

11661501610561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9381739151.

The product of its (nonzero) digits is 32400, while the sum is 40.

The spelling of 11661501610561 in words is "eleven trillion, six hundred sixty-one billion, five hundred one million, six hundred ten thousand, five hundred sixty-one".