166273117565 has 4 divisors (see below), whose sum is σ = 199527741084. Its totient is φ = 133018494048.

The previous prime is 166273117561. The next prime is 166273117583. The reversal of 166273117565 is 565711372661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 565711372661 = 191621 ⋅2952241.

It can be written as a sum of positive squares in 2 ways, for example, as 110299708996 + 55973408569 = 332114^2 + 236587^2 .

It is a cyclic number.

It is not a de Polignac number, because 166273117565 - 2² = 166273117561 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 (166273117561) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 16627311752 + ... + 16627311761.

It is an arithmetic number, because the mean of its divisors is an integer number (49881935271).

Almost surely, 2^166273117565 is an apocalyptic number.

It is an amenable number.

166273117565 is a deficient number, since it is larger than the sum of its proper divisors (33254623519).

166273117565 is an equidigital number, since it uses as much as digits as its factorization.

166273117565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33254623518.

The product of its digits is 1587600, while the sum is 50.

The spelling of 166273117565 in words is "one hundred sixty-six billion, two hundred seventy-three million, one hundred seventeen thousand, five hundred sixty-five".