13616561 has 6 divisors (see below), whose sum is σ = 15839730. Its totient is φ = 11671296.

The previous prime is 13616549. The next prime is 13616563. The reversal of 13616561 is 16561631.

It can be written as a sum of positive squares in only one way, i.e., 12250000 + 1366561 = 3500^2 + 1169^2 .

It is not a de Polignac number, because 13616561 - 2¹⁸ = 13354417 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (13616563) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 138896 + ... + 138993.

It is an arithmetic number, because the mean of its divisors is an integer number (2639955).

Almost surely, 2^13616561 is an apocalyptic number.

It is an amenable number.

13616561 is a deficient number, since it is larger than the sum of its proper divisors (2223169).

13616561 is an equidigital number, since it uses as much as digits as its factorization.

13616561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277903 (or 277896 counting only the distinct ones).

The product of its digits is 3240, while the sum is 29.

The square root of 13616561 is about 3690.0624655959. The cubic root of 13616561 is about 238.7934876879.

The spelling of 13616561 in words is "thirteen million, six hundred sixteen thousand, five hundred sixty-one".