13663656661 has 4 divisors (see below), whose sum is σ = 13664305152. Its totient is φ = 13663008172.

The previous prime is 13663656647. The next prime is 13663656691. The reversal of 13663656661 is 16665636631.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 13663656661 - 2¹⁵ = 13663623893 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13663656691) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 291541 + ... + 335146.

It is an arithmetic number, because the mean of its divisors is an integer number (3416076288).

Almost surely, 2^13663656661 is an apocalyptic number.

It is an amenable number.

13663656661 is a deficient number, since it is larger than the sum of its proper divisors (648491).

13663656661 is an equidigital number, since it uses as much as digits as its factorization.

13663656661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 648490.

The product of its digits is 2099520, while the sum is 49.

The spelling of 13663656661 in words is "thirteen billion, six hundred sixty-three million, six hundred fifty-six thousand, six hundred sixty-one".