13563661 has 4 divisors (see below), whose sum is σ = 13894524. Its totient is φ = 13232800.

The previous prime is 13563653. The next prime is 13563673. The reversal of 13563661 is 16636531.

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 7946761 + 5616900 = 2819^2 + 2370^2 .

It is a cyclic number.

It is not a de Polignac number, because 13563661 - 2³ = 13563653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13563961) 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, 165370 + ... + 165451.

It is an arithmetic number, because the mean of its divisors is an integer number (3473631).

Almost surely, 2^13563661 is an apocalyptic number.

It is an amenable number.

13563661 is a deficient number, since it is larger than the sum of its proper divisors (330863).

13563661 is an equidigital number, since it uses as much as digits as its factorization.

13563661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 330862.

The product of its digits is 9720, while the sum is 31.

The square root of 13563661 is about 3682.8875899218. The cubic root of 13563661 is about 238.4838507818.

The spelling of 13563661 in words is "thirteen million, five hundred sixty-three thousand, six hundred sixty-one".