13666356561 has 32 divisors (see below), whose sum is σ = 21619463040. Its totient is φ = 7569792000.

The previous prime is 13666356547. The next prime is 13666356581. The reversal of 13666356561 is 16565366631.

It is not a de Polignac number, because 13666356561 - 2⁶ = 13666356497 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 13666356561.

It is not an unprimeable number, because it can be changed into a prime (13666356511) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 114376 + ... + 201033.

It is an arithmetic number, because the mean of its divisors is an integer number (675608220).

Almost surely, 2^13666356561 is an apocalyptic number.

13666356561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

13666356561 is a deficient number, since it is larger than the sum of its proper divisors (7953106479).

13666356561 is a wasteful number, since it uses less digits than its factorization.

13666356561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315537.

The product of its digits is 1749600, while the sum is 48.

The spelling of 13666356561 in words is "thirteen billion, six hundred sixty-six million, three hundred fifty-six thousand, five hundred sixty-one".