165818406687 has 4 divisors (see below), whose sum is σ = 221091208920. Its totient is φ = 110545604456.

The previous prime is 165818406673. The next prime is 165818406709. The reversal of 165818406687 is 786604818561.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 786604818561 = 3 ⋅262201606187.

It is a cyclic number.

It is not a de Polignac number, because 165818406687 - 2¹⁶ = 165818341151 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 165818406687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165818406617) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27636401112 + ... + 27636401117.

It is an arithmetic number, because the mean of its divisors is an integer number (55272802230).

Almost surely, 2^165818406687 is an apocalyptic number.

165818406687 is a deficient number, since it is larger than the sum of its proper divisors (55272802233).

165818406687 is an equidigital number, since it uses as much as digits as its factorization.

165818406687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55272802232.

The product of its (nonzero) digits is 15482880, while the sum is 60.

The spelling of 165818406687 in words is "one hundred sixty-five billion, eight hundred eighteen million, four hundred six thousand, six hundred eighty-seven".