165666663651541 has 4 divisors (see below), whose sum is σ = 178410253163212. Its totient is φ = 152923074139872.

The previous prime is 165666663651523. The next prime is 165666663651563. The reversal of 165666663651541 is 145156366666561.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9188355312900 + 156478308338641 = 3031230^2 + 12509129^2 .

It is a cyclic number.

It is not a de Polignac number, because 165666663651541 - 2⁷ = 165666663651413 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 (165666663652541) 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, 6371794755816 + ... + 6371794755841.

It is an arithmetic number, because the mean of its divisors is an integer number (44602563290803).

Almost surely, 2^{165666663651541} is an apocalyptic number.

It is an amenable number.

165666663651541 is a deficient number, since it is larger than the sum of its proper divisors (12743589511671).

165666663651541 is a wasteful number, since it uses less digits than its factorization.

165666663651541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12743589511670.

The product of its digits is 419904000, while the sum is 67.

The spelling of 165666663651541 in words is "one hundred sixty-five trillion, six hundred sixty-six billion, six hundred sixty-three million, six hundred fifty-one thousand, five hundred forty-one".