13661365657 has 4 divisors (see below), whose sum is σ = 13677382180. Its totient is φ = 13645349136.

The previous prime is 13661365651. The next prime is 13661365709. The reversal of 13661365657 is 75656316631.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4929584521 + 8731781136 = 70211^2 + 93444^2 .

It is a cyclic number.

It is not a de Polignac number, because 13661365657 - 2¹¹ = 13661363609 is a prime.

It is a super-2 number, since 2×13661365657² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 13661365657.

It is not an unprimeable number, because it can be changed into a prime (13661365651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8006982 + ... + 8008687.

It is an arithmetic number, because the mean of its divisors is an integer number (3419345545).

Almost surely, 2^13661365657 is an apocalyptic number.

It is an amenable number.

13661365657 is a deficient number, since it is larger than the sum of its proper divisors (16016523).

13661365657 is an equidigital number, since it uses as much as digits as its factorization.

13661365657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16016522.

The product of its digits is 2041200, while the sum is 49.

The spelling of 13661365657 in words is "thirteen billion, six hundred sixty-one million, three hundred sixty-five thousand, six hundred fifty-seven".