11555541987557 has 2 divisors, whose sum is σ = 11555541987558. Its totient is φ = 11555541987556.

The previous prime is 11555541987553. The next prime is 11555541987593. The reversal of 11555541987557 is 75578914555511.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9769881713761 + 1785660273796 = 3125681^2 + 1336286^2 .

It is a cyclic number.

It is not a de Polignac number, because 11555541987557 - 2² = 11555541987553 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (11555541987551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5777770993778 + 5777770993779.

It is an arithmetic number, because the mean of its divisors is an integer number (5777770993779).

Almost surely, 2^{11555541987557} is an apocalyptic number.

It is an amenable number.

11555541987557 is a deficient number, since it is larger than the sum of its proper divisors (1).

11555541987557 is an equidigital number, since it uses as much as digits as its factorization.

11555541987557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 220500000, while the sum is 68.

The spelling of 11555541987557 in words is "eleven trillion, five hundred fifty-five billion, five hundred forty-one million, nine hundred eighty-seven thousand, five hundred fifty-seven".