166177681 has 2 divisors, whose sum is σ = 166177682. Its totient is φ = 166177680.

The previous prime is 166177679. The next prime is 166177721. The reversal of 166177681 is 186771661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 162792081 + 3385600 = 12759^2 + 1840^2 .

It is a cyclic number.

It is not a de Polignac number, because 166177681 - 2¹ = 166177679 is a prime.

It is a super-5 number, since 5×166177681⁵ (a number of 42 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

Together with 166177679, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (166177651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83088840 + 83088841.

It is an arithmetic number, because the mean of its divisors is an integer number (83088841).

Almost surely, 2^166177681 is an apocalyptic number.

It is an amenable number.

166177681 is a deficient number, since it is larger than the sum of its proper divisors (1).

166177681 is an equidigital number, since it uses as much as digits as its factorization.

166177681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 43.

The square root of 166177681 is about 12890.9922426476. The cubic root of 166177681 is about 549.7824825812.

The spelling of 166177681 in words is "one hundred sixty-six million, one hundred seventy-seven thousand, six hundred eighty-one".