166578242875661 has 2 divisors, whose sum is σ = 166578242875662. Its totient is φ = 166578242875660.

The previous prime is 166578242875651. The next prime is 166578242875753.

It is a happy number.

166578242875661 is nontrivially palindromic in base 10.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 94782277313161 + 71795965562500 = 9735619^2 + 8473250^2 .

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 166578242875661 - 2¹⁴ = 166578242859277 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166578242875651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83289121437830 + 83289121437831.

It is an arithmetic number, because the mean of its divisors is an integer number (83289121437831).

Almost surely, 2^{166578242875661} is an apocalyptic number.

It is an amenable number.

166578242875661 is a deficient number, since it is larger than the sum of its proper divisors (1).

166578242875661 is an equidigital number, since it uses as much as digits as its factorization.

166578242875661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1625702400, while the sum is 74.

The spelling of 166578242875661 in words is "one hundred sixty-six trillion, five hundred seventy-eight billion, two hundred forty-two million, eight hundred seventy-five thousand, six hundred sixty-one".