11987057561 has 8 divisors (see below), whose sum is σ = 12823027560. Its totient is φ = 11165626368.

The previous prime is 11987057549. The next prime is 11987057581. The reversal of 11987057561 is 16575078911.

It can be written as a sum of positive squares in 4 ways, for example, as 1143792400 + 10843265161 = 33820^2 + 104131^2 .

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-11987057561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11987057521) 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, 3632996 + ... + 3636293.

It is an arithmetic number, because the mean of its divisors is an integer number (1602878445).

Almost surely, 2^11987057561 is an apocalyptic number.

It is an amenable number.

11987057561 is a deficient number, since it is larger than the sum of its proper divisors (835969999).

11987057561 is an equidigital number, since it uses as much as digits as its factorization.

11987057561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7269403.

The product of its (nonzero) digits is 529200, while the sum is 50.

The spelling of 11987057561 in words is "eleven billion, nine hundred eighty-seven million, fifty-seven thousand, five hundred sixty-one".