16555232878181 has 2 divisors, whose sum is σ = 16555232878182. Its totient is φ = 16555232878180.

The previous prime is 16555232878139. The next prime is 16555232878183. The reversal of 16555232878181 is 18187823255561.

16555232878181 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14352504940900 + 2202727937281 = 3788470^2 + 1484159^2 .

It is a cyclic number.

It is not a de Polignac number, because 16555232878181 - 2³⁰ = 16554159136357 is a prime.

It is a super-2 number, since 2×16555232878181² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 16555232878183, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16555232878183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8277616439090 + 8277616439091.

It is an arithmetic number, because the mean of its divisors is an integer number (8277616439091).

Almost surely, 2^{16555232878181} is an apocalyptic number.

It is an amenable number.

16555232878181 is a deficient number, since it is larger than the sum of its proper divisors (1).

16555232878181 is an equidigital number, since it uses as much as digits as its factorization.

16555232878181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32256000, while the sum is 62.

The spelling of 16555232878181 in words is "sixteen trillion, five hundred fifty-five billion, two hundred thirty-two million, eight hundred seventy-eight thousand, one hundred eighty-one".