11635561 has 4 divisors (see below), whose sum is σ = 13297792. Its totient is φ = 9973332.

The previous prime is 11635553. The next prime is 11635579. The reversal of 11635561 is 16553611.

11635561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16553611 = 1297 ⋅12763.

It is a cyclic number.

It is not a de Polignac number, because 11635561 - 2³ = 11635553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11635661) 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, 831105 + ... + 831118.

It is an arithmetic number, because the mean of its divisors is an integer number (3324448).

Almost surely, 2^11635561 is an apocalyptic number.

It is an amenable number.

11635561 is a deficient number, since it is larger than the sum of its proper divisors (1662231).

11635561 is an equidigital number, since it uses as much as digits as its factorization.

11635561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1662230.

The product of its digits is 2700, while the sum is 28.

The square root of 11635561 is about 3411.0938128407. The cubic root of 11635561 is about 226.6013236774.

It can be divided in two parts, 1163 and 5561, that added together give a square (6724 = 82²).

The spelling of 11635561 in words is "eleven million, six hundred thirty-five thousand, five hundred sixty-one".