11665553681 has 4 divisors (see below), whose sum is σ = 11667265764. Its totient is φ = 11663841600.

The previous prime is 11665553651. The next prime is 11665553719. The reversal of 11665553681 is 18635556611.

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 3941956225 + 7723597456 = 62785^2 + 87884^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11665553681 is a prime.

It is a super-2 number, since 2×11665553681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11665553651) 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, 845780 + ... + 859461.

It is an arithmetic number, because the mean of its divisors is an integer number (2916816441).

Almost surely, 2^11665553681 is an apocalyptic number.

It is an amenable number.

11665553681 is a deficient number, since it is larger than the sum of its proper divisors (1712083).

11665553681 is an equidigital number, since it uses as much as digits as its factorization.

11665553681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1712082.

The product of its digits is 648000, while the sum is 47.

The spelling of 11665553681 in words is "eleven billion, six hundred sixty-five million, five hundred fifty-three thousand, six hundred eighty-one".