13665581 has 4 divisors (see below), whose sum is σ = 13773312. Its totient is φ = 13557852.

The previous prime is 13665577. The next prime is 13665593. The reversal of 13665581 is 18556631.

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 13665581 - 2² = 13665577 is a prime.

It is a super-2 number, since 2×13665581² = 373496208135122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13665511) 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, 53675 + ... + 53928.

It is an arithmetic number, because the mean of its divisors is an integer number (3443328).

Almost surely, 2^13665581 is an apocalyptic number.

It is an amenable number.

13665581 is a deficient number, since it is larger than the sum of its proper divisors (107731).

13665581 is a wasteful number, since it uses less digits than its factorization.

13665581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107730.

The product of its digits is 21600, while the sum is 35.

The square root of 13665581 is about 3696.6986623202. The cubic root of 13665581 is about 239.0796989150.

The spelling of 13665581 in words is "thirteen million, six hundred sixty-five thousand, five hundred eighty-one".