165811553687 has 4 divisors (see below), whose sum is σ = 178566288600. Its totient is φ = 153056818776.

The previous prime is 165811553647. The next prime is 165811553689. The reversal of 165811553687 is 786355118561.

165811553687 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 786355118561 = 15737 ⋅49968553.

It is a cyclic number.

It is not a de Polignac number, because 165811553687 - 2⁸ = 165811553431 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165811553689) 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, 6377367437 + ... + 6377367462.

It is an arithmetic number, because the mean of its divisors is an integer number (44641572150).

Almost surely, 2^165811553687 is an apocalyptic number.

165811553687 is a deficient number, since it is larger than the sum of its proper divisors (12754734913).

165811553687 is a wasteful number, since it uses less digits than its factorization.

165811553687 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12754734912.

The product of its digits is 6048000, while the sum is 56.

The spelling of 165811553687 in words is "one hundred sixty-five billion, eight hundred eleven million, five hundred fifty-three thousand, six hundred eighty-seven".