11661556501566 has 32 divisors (see below), whose sum is σ = 26750523878400. Its totient is φ = 3761792419320.

The previous prime is 11661556501547. The next prime is 11661556501613. The reversal of 11661556501566 is 66510565516611.

11661556501566 is a `hidden beast` number, since 1 + 1 + 6 + 6 + 1 + 5 + 565 + 0 + 15 + 66 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3483139456 + ... + 3483142803.

It is an arithmetic number, because the mean of its divisors is an integer number (835953871200).

Almost surely, 2^{11661556501566} is an apocalyptic number.

11661556501566 is an abundant number, since it is smaller than the sum of its proper divisors (15088967376834).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

11661556501566 is a wasteful number, since it uses less digits than its factorization.

11661556501566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6966282301 (or 6966282295 counting only the distinct ones).

The product of its (nonzero) digits is 4860000, while the sum is 54.

The spelling of 11661556501566 in words is "eleven trillion, six hundred sixty-one billion, five hundred fifty-six million, five hundred one thousand, five hundred sixty-six".