11641603561 has 4 divisors (see below), whose sum is σ = 13304689792. Its totient is φ = 9978517332.

The previous prime is 11641603517. The next prime is 11641603579. The reversal of 11641603561 is 16530614611.

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: 16530614611 = 7 ⋅2361516373.

It is not a de Polignac number, because 11641603561 - 2⁹ = 11641603049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11641603261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 831543105 + ... + 831543118.

It is an arithmetic number, because the mean of its divisors is an integer number (3326172448).

Almost surely, 2^11641603561 is an apocalyptic number.

It is an amenable number.

11641603561 is a deficient number, since it is larger than the sum of its proper divisors (1663086231).

11641603561 is an equidigital number, since it uses as much as digits as its factorization.

11641603561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1663086230.

The product of its (nonzero) digits is 12960, while the sum is 34.

The spelling of 11641603561 in words is "eleven billion, six hundred forty-one million, six hundred three thousand, five hundred sixty-one".