165811855787 has 8 divisors (see below), whose sum is σ = 166918484304. Its totient is φ = 164706317568.

The previous prime is 165811855757. The next prime is 165811855789. The reversal of 165811855787 is 787558118561.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 165811855787 - 2¹⁸ = 165811593643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165811855789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33743 + ... + 576855.

It is an arithmetic number, because the mean of its divisors is an integer number (20864810538).

Almost surely, 2^165811855787 is an apocalyptic number.

165811855787 is a deficient number, since it is larger than the sum of its proper divisors (1106628517).

165811855787 is a wasteful number, since it uses less digits than its factorization.

165811855787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 545149.

The product of its digits is 18816000, while the sum is 62.

The spelling of 165811855787 in words is "one hundred sixty-five billion, eight hundred eleven million, eight hundred fifty-five thousand, seven hundred eighty-seven".