165855595991 has 8 divisors (see below), whose sum is σ = 167083896720. Its totient is φ = 164630394432.

The previous prime is 165855595957. The next prime is 165855596003. The reversal of 165855595991 is 199595558561.

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-165855595991 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 (165855595921) 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, 667310 + ... + 881483.

It is an arithmetic number, because the mean of its divisors is an integer number (20885487090).

Almost surely, 2^165855595991 is an apocalyptic number.

165855595991 is a deficient number, since it is larger than the sum of its proper divisors (1228300729).

165855595991 is a wasteful number, since it uses less digits than its factorization.

165855595991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1549585.

The product of its digits is 109350000, while the sum is 68.

The spelling of 165855595991 in words is "one hundred sixty-five billion, eight hundred fifty-five million, five hundred ninety-five thousand, nine hundred ninety-one".