11721323561 has 8 divisors (see below), whose sum is σ = 11987823744. Its totient is φ = 11455536400.

The previous prime is 11721323531. The next prime is 11721323563. The reversal of 11721323561 is 16532312711.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11721323561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11721323563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 144935 + ... + 210828.

It is an arithmetic number, because the mean of its divisors is an integer number (1498477968).

Almost surely, 2^11721323561 is an apocalyptic number.

It is an amenable number.

11721323561 is a deficient number, since it is larger than the sum of its proper divisors (266500183).

11721323561 is an equidigital number, since it uses as much as digits as its factorization.

11721323561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356511.

The product of its digits is 7560, while the sum is 32.

The spelling of 11721323561 in words is "eleven billion, seven hundred twenty-one million, three hundred twenty-three thousand, five hundred sixty-one".