66191810165 has 8 divisors (see below), whose sum is σ = 85540185528. Its totient is φ = 48880105920.

The previous prime is 66191810149. The next prime is 66191810183. The reversal of 66191810165 is 56101819166.

It can be written as a sum of positive squares in 4 ways, for example, as 790396996 + 65401413169 = 28114^2 + 255737^2 .

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

It is not a de Polignac number, because 66191810165 - 2⁴ = 66191810149 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 509167706 + ... + 509167835.

It is an arithmetic number, because the mean of its divisors is an integer number (10692523191).

Almost surely, 2^66191810165 is an apocalyptic number.

66191810165 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66191810165 is a deficient number, since it is larger than the sum of its proper divisors (19348375363).

66191810165 is a wasteful number, since it uses less digits than its factorization.

66191810165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1018335559.

The product of its (nonzero) digits is 77760, while the sum is 44.

The spelling of 66191810165 in words is "sixty-six billion, one hundred ninety-one million, eight hundred ten thousand, one hundred sixty-five".