12635561 has 4 divisors (see below), whose sum is σ = 13071300. Its totient is φ = 12199824.

The previous prime is 12635531. The next prime is 12635563. The reversal of 12635561 is 16553621.

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 7595536 + 5040025 = 2756^2 + 2245^2 .

It is a cyclic number.

It is not a de Polignac number, because 12635561 - 2¹⁰ = 12634537 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 435709 = 12635561 / (1 + 2 + 6 + 3 + 5 + 5 + 6 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12635563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 217826 + ... + 217883.

It is an arithmetic number, because the mean of its divisors is an integer number (3267825).

Almost surely, 2^12635561 is an apocalyptic number.

It is an amenable number.

12635561 is a deficient number, since it is larger than the sum of its proper divisors (435739).

12635561 is an equidigital number, since it uses as much as digits as its factorization.

12635561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 435738.

The product of its digits is 5400, while the sum is 29.

The square root of 12635561 is about 3554.6534289576. The cubic root of 12635561 is about 232.9153849212.

The spelling of 12635561 in words is "twelve million, six hundred thirty-five thousand, five hundred sixty-one".