166557042661 has 2 divisors, whose sum is σ = 166557042662. Its totient is φ = 166557042660.

The previous prime is 166557042653. The next prime is 166557042677. The reversal of 166557042661 is 166240755661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 105631500100 + 60925542561 = 325010^2 + 246831^2 .

It is an emirp because it is prime and its reverse (166240755661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 166557042661 - 2³ = 166557042653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166557042611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83278521330 + 83278521331.

It is an arithmetic number, because the mean of its divisors is an integer number (83278521331).

Almost surely, 2^166557042661 is an apocalyptic number.

It is an amenable number.

166557042661 is a deficient number, since it is larger than the sum of its proper divisors (1).

166557042661 is an equidigital number, since it uses as much as digits as its factorization.

166557042661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1814400, while the sum is 49.

The spelling of 166557042661 in words is "one hundred sixty-six billion, five hundred fifty-seven million, forty-two thousand, six hundred sixty-one".